This time last year, I was travelling to Pittsburgh for Christmas. The drive from New York was over six hours and mostly uneventful, but as we got into the city, I spotted two cars I didn’t think I would ever see on the road: Dodge’s last personal luxury coupes.
The Magnum was a sharp reskin of the unpopular 1975-78 Charger. Launched for 1978, it sold alongside the moribund Charger and usurped it entirely for 1979. The exterior was extensively revised for two reasons. Firstly, the Charger had been in the sales wilderness since its restyle in 1975. An exterior far too similar to its prestigious Chrysler Cordoba clone, as well as the keen positioning of the latter, simply led to more buyers at the Chrysler showroom. Secondly, the blocky Charger simply wasn’t as good fit for NASCAR as its predecessor. A sleeker, more aerodynamic design was needed.
Enter: Magnum. Other than the new Cord-style grille, revised taillights, and rectangular composite-esque headlights (sealed beam headlights with transparent retractable covers), the Magnum was much the same as the Charger. It still rode on the aging B-Body, which would soon be put out to pasture. Engine choices were the same 318 with Lean Burn, 360 and 400 V8s, although the latter would be only offered in 1978. There was even an available GT package with heavy-duty suspension and turned metal dash appliqué. Initial sales were quite strong, and blew the dying Charger into the weeds: 55,431 vs 2,800. However, they slumped to 30,354 in 1979.
The Magnum was never going to stick around for too long, though. The B-Body platform was a big ‘un, with a 4000lb curb weight in Magnum guise, and it dated back to 1962. Richard Petty had also been particularly unimpressed with the Magnum’s high-speed handling, and there was a lack of factory development in the 360 V8 for NASCAR; he ditched the Magnum.
Dodge would ditch the Magnum after 1979, and in Chrysler’s darkest days in 1980 it would launch the striking Mirada. Based on the J body, Dodge’s personal luxury offering was once again twinned with the Chrysler Cordoba. The personal luxury twins were heavily based on the platform family underpinning the Dodge Aspen/Plymouth Volare and Dodge Diplomat/Chrysler LeBaron.
800 pounds lighter than its predecessor and 6 inches shorter, 2.3 of those in the wheelbase, the Mirada was a more manageable size. It had even more visual presence than the Magnum, though, with sharp-edged, sheer styling. Inside was similarly a breath of fresh air, with a modern and striking dash and more cabin space than the Magnum.
Motivation was provided by carryover 318 and 360 V8s (the latter would go after Mirada’s debut year) and the new base engine was Mopar’s venerable 225 cu.-in Slant Six which, despite the lighter weight of the Mirada, would be thoroughly outmatched. Once again, a sport handling package was offered with heavy-duty shock absorbers and front and rear anti-sway bars. However, once again, the Mirada didn’t succeed in NASCAR.
Sadly, the Mirada would prove to be a poor seller for Dodge. Perhaps it was a lack of marketing, or an aversion on the part of consumers towards Mopar’s pricier models in a trying time for the company, but Mirada sales would start at a low base – 32,746 – and slump year-over-year down to a meagre 5,597 units in its final year; Cordoba sales followed a similar track and bottomed out at 13,471. Chrysler was busy with its predominantly K-Car-derived lineup now, and there would be no room for the pretty Mirada or its Cordoba twin.
I love these last personal luxury coupes from Dodge and hopefully if I spot some again I can do them justice with better photographs and a more comprehensive article. Drive safely tomorrow, everybody, and may you and your families have a very Merry Christmas!
Two cars in which the timing and circumstances, particularly for the Mirada, were a perfect storm working against it. Either would be welcome in my garage.
The Magnum fooled me at the time; despite the identical greenhouse to the Cordoba I didn’t fully see its Cordoba/Challenger roots. And the Mirada always fooled me — until this article I didn’t know about its Aspen/Volare roorts.
In Pennsylvania, land of the ugly brown flakes underneath cars and the corrupt annual inspection racket, both of these have to be regarded as lucky survivors. Both seem to have a future, the Magnum with its repaired rear quarter and the Mirada, which has obviously seen some care over the decades.
What do the dual exhausts on the MIrada suggest?
But then again, what lurks in the background of the last Mirada photo? It would seem there is a car guy around there.
Pennsylvania’s annual inspection corruption racket – my wife and I lived in Hershey from 1999 to 2000 and I was amused to discover that my wife’s 1 year old Mustang and my one month old Nissan were denied passing inspections due to “headlight alignment”, which they could fix on the spot of course. I declined and took both vehicles to the local dealers for a warranty claim. Both were in perfect factory spec of course.
I chalked it up to the misconception by many northerners that everyone from the south is an ignorant redneck. I was working for Norfolk Southern at the time and was in the first wave of people sent up north when NS and CSX obtained Conrail. The former Conrail people had a lot of fun teasing us about being ignorant hicks, which we found amusing as we were the ones who actually knew how to run a consistently profitable railroad.
Indiana used to have a yearly inspection also. Some garages would pass anything as long as you paid the initial fee. You could always find someone to pass your clunker. The whole thing was ridiculous. They finally did away with it altogether. In fact, unless some of the northern counties have it, there are no emissions checks either.
Well here in the Southern Tier we call the Northern Tier and points south Pennsyltucky which I am sure you have heard before. Course they call us Damn Yankees right back.
I do remember Conrail people and hearing from their kids I went to school with being pissed off that *inappropriate name* aka Norfolk Southern and *inappropriate name* aka CSXT bought out their superior railroad.
I have no doubt that Conrail was a superior railroad to work for from what I could gather. NS demands so much of their non-union officers. After a couple of years, I took a huge pay cut and chose family life over living between the two rails.
The Conrail people also had the historical memory of the magnificent Pennsylvania Railroad and New York Central Railroad before their declines and the eventual government intervention that formed Conrail.
And I worked for the New York Central, the world’s greatest railroad and predecessor to Conrail. I also had a cousin who husband was superintendent of Southern RR from Cincinnati to Chattanooga. In days of yore, the Southern was decidedly inferior to the NYC, So there!
There is no doubt, unless you are a Pennsy guy! As a civil engineer I was very impressed by the infrastructure built by both that I worked on in PA, NJ, and NY.
When we would take family rail trips, my father who worked for the NYC for nearly 40 years, would remark how good it was to get back on the home line after riding the comparatively rough rails of other roads.
Before the late 50’s nearly all of the line was double tracked with four sets between Buffalo and New York City. As an engineer, you would have been proud.
Zipster, my paternal grandfather was an NYC retiree and my father was an NYC fan. He never could figure out why his second son (me 🙂 ) turned out to be a Pennsy fan!
So how was the Mustang/Nissan misaligned headlight issue ultimately resolved? I would hope that showing them the service departments’ documentation would have been sufficient.
I took them back to the garage and they were in spec on the second check. They were real pals and didn’t charge me for the second inspection. I’m guessing the inspection garage was the crook in this case, but who knows, the dealer may have adjusted the lights.
I found another garage for routine maintenance and the following year’s inspection. Fool me once and all of that. Cars are like women, they are a pain in the ass and something is always wrong, so why do shops have to make up problems when there are plenty of real ones.
Growing up in the Southern Tier meant that I was often exposed to the realities as well as quirks of both states’ emissions and/or safety programs. Also, vehicles rust slower in PA especially the closer you get to the Mason Dixon line due to state policies when it comes to dealing with Winter weather.
New York has statewide emissions testing, but all I have to do is drive 30 miles south to Sayre and there is no emissions testing. In PA a rust hole bigger than a Quarter will flunk you, but not in New York.
So a dichotomy develops since you can end up with a vehicle where it is not economical to repair the emissions system and keep it New York, but it is also not economical to repair the rust holes so you can register it in PA. Not sure about PA, but at least around here vehicles can pass the emissions and/or safety inspection if you know someone or know where to go. Course you can always send the vehicle to Ohio, Indiana, Michigan, or Jersey which I have seen happen, none of those places have safety testing and only Jersey has emissions testing.
This Silverado is a perfect example. Just bring it up to NY and drive it for a few more years, or more if you want to repair the rust.
We down in FL HAD emissons inspections until Hurrcane Andrew blew the stations away. TheEPA said FL had to rebuild them, but like 1% or less failed and the air stayed clean so FL said why bother. THe EPA said they would pull fed money so FL said they wouldn’t send what they collected to DC so the EPA caved. One win for the good guys.We do have rust prblems down here due to sea salt. A friend of mine with a Corvette got his entire frame replaced (83 vette) by Chevy due to the rust giving him only essensce of frame after only 3 years..
I could put up with one of these and Blue Oyster Cult’s Spectres on the 8 track for a Saturday night cruiser.I’ve seen the occasional one at the Mopar Euronats show but they’re a rarity compared to B bodies.
I had a serious man-crush on these when they were new. I would still happily adopt and drive one. I was particularly smitten with the Mirada.
The Mirada was a poor seller because every Mopar in 1980-81 that was not an L or K body car was a poor seller. Chrysler’s quality rep was in the toilet and the company’s viability was in doubt. At the time though, I thought they would sell better than they did. I also thought that Iacocca cancelled them just as market conditions and fuel prices were turning around.
Leave it to Imacoocoo to cancel anything that had a V8 in it. The boy thought everything needed to be a front wheel drive 4 banger pile of crap.
Those front-drive, 4 banger “pieces of crap” are what saved Chrysler the first time around.
Actually the K cars were solid, well made and offered real performance with some Shelby stank rubbed off on them. Im a v8 rwd guy myself, but there IS a place for fast and scrappy turbo 4 cyl cars too. I agree V8s and rwd shouldn’t have been wholesale scrapped the way they were, but if you were to square off against a Daytona IROC R/T, then you better have eaten your Wheaties.
In the late ’70s and early ’80s, there was a general presumption that V-8s were on the way out. Everyone assumed that oil prices were going to continue to escalate and CAFE requirements looked to continue climbing until they hit 35 mpg by the latter ’80s. The idea that gasoline prices would go down to basically their ’50s-60s levels (inflation-adjusted) would have been laughed off as wishful thinking. The rest of the industry was thinking the same thing, but they didn’t get quite so far with their all-four-or-six plans.
I’m a big fan of this generation Cordoba and Mirada, and always wonder about if they were not discontinued so soon. If they were hypothetically refined a bit over the next couple of years, I think they could’ve sold well into the mid-to-late 1980s, as the the G-body Cutlass Supreme/Regal/Grand Prix/Monte Carlo certainly held their own in the face of newer competitors.
If they’d hung around one more year, we would’ve had an interesting spread from the knife-edge Mopars, through the mini-neoclassical GM G bodies, to the aero Ford coupes. I do like the Mirada, but I’m afraid it would have been obiliterated by the combination of Ford and GM.
I would like to think if the Mirada/Cordoba had somehow survived the K car clone onslaught that it would have done fairly well against the G-body GMs and the Fox body T-bird/Cougar. Like JPC noted before, by 1980 Chrysler’s reputation was in the toilet.
I knew a number of people who absolutely would not touch one of those cars during that time period due to the idea of owning an “orphan”. I think the fears of folks who ended up with Studebakers in the 1960’s were still part of the car buying consciousness in the late 1970’s early 1980’s.
The L-body and K-body FWD Mopars were a “reboot” of the company in many ways. Lido (love him or hate him, along with Bob Lutz) did one hell of a sales job for Chrysler and the K-cars and it worked.
With the survival of the M-bodies, I think possibly the Mirada/Cordoba (or maybe just one of them) could have survived, too. I would imagine the Cordoba would have been more likely to survive, as it could be priced high enough to make up for it’s relative small production numbers. And it would have been a more appropriate companion to the RWD Fifth Avenue than the FWD LeBaron coupes (no matter how much I liked them). I think there was enough “brand equity” in the Cordoba name that it could have worked.
Let’s face it, the Fox body Thunderbird and Cougar were the only personal coupes that evolved throughout the 1980’s. The G-body coupes from GM were pretty much static since 1981 to the end of the run in 1987. With the exceptions of models like the Grand Prix and Monte Carlo Aerocoupes, the Olds Hurst and 442 special editions, and the GN & GNX variants, the meat of the sales were regular versions of those cars. The hot rod versions were basically outliers in terms of sales.
If Chrysler had adopted a similar strategy with the Cordoba, I believe it could have survived until the late 1980’s. I think it could have reasonably taken over where the 1980-82 Imperial left off, with the right packaging. Maybe possibly they could have done a CMX version with a longitudinal version of the 2.2 turbo, similar to the Thunderbird Turbo Coupe. By the mid 1980’s, the K car had made enough money that Lido could buy Lamborghini and an aircraft company (that escapes me now). Maybe they could have shaken a few dollars to make a competitive coupe?
I like the looks of those last-generation Miradas and Cordobas, especially with the red and white bucket-seat interior. But those stylish dashes had switchgear that felt tinny and cheap to me, raised as I was on 50’s and 60’s Mopar cars.
It’s not blurry, that’s how all Miradas look!
Dodge needs to get some of these vehicles in their ads since it is pathetic that nearly 50 years of history is skipped.
I noticed that too!
Still, it’s well made, with a nice twist at the end.
If Dodge were interested in showing a basic timeline from every era, it would be a different kind of commercial. But for choosing examples showing performance improvement with memorable cars, they didn’t do badly. It could be argued that the Super Bee (or whatever that is) can symbolize performance for the entire missing era, as cars changed their looks but didn’t get significantly faster or better handling. You don’t want to show both old and new Challengers. It’s repetitive. Plus, some would say the current one suffers in the looks dept. by comparison.
The ’39/’40 might not be an obvious choice, but it was the last body before Mopars got bulbous and pedestrian looking, and stayed that way ’til the ’55/’56 introduction. I might have used a ’57 in that spot, but then there were the quality issues. ’55s never had them. They were arguably prettier too.
We all know about the 700 hp Challenger, and the Alfa based Dart is widely considered a terrific performer, so I’m good with this. I love the Viper surprise at the end, too.
Whether or not the Dodge Brothers were the wild and crazy guys portrayed is a matter of history, which always gets a re-skin anyway, especially when performance is the thing being sold.
As a Mopar guy, I’m happy to see this kind of ad from them.
“As a Mopar guy, I’m happy to see this kind of ad from them.”
Agree. And Im glad that Chrysler seems to be embracing its heritage/image as a car company for car enthusiasts. Granted, that wont outsell the faceless hordes of cammaccords, but what it WILL do is establish a solid base of loyal repeat customers and steady revenue. IF they can continue to deliver performance and style mixed with reliability and affordability.
I may be a Ford guy but I can appreciate the right car of about any make. I have even owned a couple of MOPARs myself, a’35 Plymouth street rod and a ’99 Dakota. Back in the ’70’s I also had a ’34 Desoto Airflow that I dug out of a barn lot and planned to restore. I finally sold it when I realized that it would be too much for my talent and finances at the time.
These ads are the only ones on TV that I will stop and watch all the way through. Quite creative.
I think I do remember reading one time that the Dodge Brothers liked to drink but I also don’t know about the wild and crazy part.
Agree 100%!!!! Dodge’s lineup has always offered something interesting even in the darkest of times.
Yeah, there’s a void, but I see the reason. I really like this ad, and it definitely plays to the Hipsters with the prohibition-Boardwalk Empire styling of the actors. (Very big here in NYC, where there’s a flapper dance party twice every summer on Governors Island.)
The one thing that jars me as a Mopar guy, but certainly not the general population, is that John and Horace Dodge were 50 and 46 respectively when they launched Dodge – not the low-twenties lads you see here.
I remember the Mirada as a very pretty version of a body style I was beginning to consider an anachronism when it was introduced. I was just turning 30, and for me, a “personal coupe” would have to be much smaller and fit in with my newly acquired sense of “personal maturity”. So, though I found it beautiful, the Miranda didn’t fit with image I was trying to project. Neither could I afford a car in that class. I bought a Phoenix.
But, IMHO, Dodge took the Cordoba idea out of its roundeyed, turret-top roots into a clean and airy direction with the Mirada that was more portentous of future design than the pro wrestler Magnum. The latter was impressive with its dieselectric snout, but the tiny opera windows on it and most other personal coupes seemed to try too hard to embody the Dashing Single Man. Enlarging them on the Mirada allowed for Ted and Alice to ride along in the back of Bob and Carol’s car where the public could see all four swingers.
Those wheels look great, too (though I can’t recall ever seeing one without white wallis). The car didn’t/doesn’t seem to have a controversial line on it, but takes no chances. Guess it was one of those designs that was doomed to failure by timing, despite good looks.
A friend of mine had a Mirada – white with a red velour interior. It was really nice looking. Much more than the Thunderbird. They were built in my home town so there were pretty much everywhere (along with the Mirada/Cordoba).
One thing that I never noticed until now. The roof treatment on the silver model in the brochure mimics that found on the ’77-’79 T-Bird and the Fairmont Futura.
My daily driver is an 81 Mirada CMX. It’s not exactly box stock but it’s still on the road. At least for now. I’m going to freshen it up at the beginning of the year. The last time I ‘freshened up’ a car it took me a year and a half.
Got pics? Id like to see it.
Kinda like the front end clip on the Magnum. Reminds me of a Cord 810.
I have always loved the Mirada. I like the square edged style, especially in light of all the rounded cars that have come since. You can actually tell what these are from a distance. In 1981 I had my choice of what company car to buy. I was strongly considering one of these but ended up being getting a Buick Regal coupe. It was a nice car, but lacked the individuality and personality of the Mirada I think.
Merry Christmas to all !
Merry Christmas from Pittsburgh!
Although I can’t place the exact locations of the photos they look like home to me.
Have to admit I never cared for the Mirada, although I did like the Charger re-skin. Always imagined one with classic MoPar motorvation…even a mild 383 would wake it up nicely.
Yes, these photos look like Pittsburgh to me too. Although I’m from the Youngstown, Ohio area, my wife is from the South Hills of Pittsburgh. I spent plenty of time traveling down there for various reasons, (remember the Syria Mosque? I saw some great concerts there back in the day…) and with much her family still down there, we still get down there at least once a year.
What clues to me to the fact that these photos are in-city Pittsburgh is the relationship of the parking areas to the street. I live in the Upper Midwest now, and even in the big cities you usually have a decent sized sidewalk between a parking lot and the street. In “da Burgh”, the parking and store fronts are almost on the street. One wrong move and you’ll end up in some orthodontists waiting room!
Alright, my Dad’s second car gets a day in the spotlight! I think that covers all the “classics” my parents owned, up to the ’96 Grand Caravan.
I’ve always liked the Dodge Mirada and later Cordoba.
Ive never been able to like the Magnum’s bodystyle no matter how hard I try. It just doesn’t come off ‘muscle car’ enough. I know, I know…this was the broughamtastic personal luxury era. And yet, the contemporary Cutlass still seemed to have that swagger when trimmed properly. Even the Cordoba and its Charger clone seemed to have a little something that these didn’t which appeal to my hotrodder sensibilities. Maybe the squared off look doesn’t sit right. But ‘Magnum’ is one hell of a nameplate. How they ditched that for the much more soft/friendly ‘Mirada’ name I’ll never understand.
That said, I love the J-bodies…well the Mirada and the LS version of the Cordoba, anyway. They look sharp when sitting on blackwalls and mag wheels, and in the right colors. Jason S nailed it though…the deck was stacked against these cars, and the actual marketing/execution left a lot to be desired. Id love a solid red T-Top Cordoba LS. Love the crosshair grille over the Mirada;s eggcrate. Id have to swap in a hot 360 and a 4spd. AND grab some ‘Magnum’ badges to make that car what it shoudlve been all along….
I just remembered, Ideal had the Magnum bodystyle for their TCR line of slotless electric racing. I have a couple of these buried in my collection somewhere:
Aurora AFX had some too. If only the real thing were proportioned like this:
My oldest nephew bought a new Charger in 1976. It was large, handled badly, had poor build quality, was trouble prone, and had rust perforation in the trunk dropoffs in less than 2 years. Other than that it was a nice car.
There has been a dark red Mirada in incredible condition for sale around here for some time. Every time I see it at a show the price seems to go down. I like that body style a lot, just not enough to want one.
These are rare finds.
Arent you up in WA state? If so I may have seen that car on the list of Craig. Dark red, white top and seats. Its in amazing shape. Its a 318 car with the 40/20/40 bench and column shift TF so a bit shy of the ‘ultimate’ Mirada considering they wanted $6500 last time I saw it. With a 360, full buckets and floor shift, itd be hard to pass up at that point.
Wisconsin. I don’t know how it survived this long, unless it is from a non-salt state. I’ve never seen the owner around it to ask. There are a lot of Mopar fans in Kenosha.
I am surprised that the two feature cars are in as good of shape body-wise as they are considering the location with the snowy winters….I have seen cars newer than 2000 with rotted out fenders and the like in the mountains of Western PA……Back in the 70’s and 80’s, you’d see 5 year old cars and trucks in that region filled with bondo body filler to hide the rust holes….Mudflaps sold very well at autoparts stores as people mounted them behind the fender wheel openings to keep salt and dirt from splashing up behind the tires onto rocker panels and quarter panels.
Other than being a 2 door personal luxury coupe, the Mirada never did much for me. Back then. I would love to own one now. The Magnum was another matter. Using the same body as the Charger and Cordoba, I loved it’s styling. I remember a neighbor back then buying a brand new triple white one. White paint, vinyl top, and interior. It had a red pinstripe just below the beltline. That was one gorgeous car. I would REALLY like to have one of those today. At one point, before front wheel drive reared it’s ugly head and the jellybean look became the in thing, American manufacturers did indeed build some awesome cars.
I’ve always liked the Dodge Mirada’s a lot and never understood why they didn’t sell very well, I always thought they were much better looking than the Ford T-Bird’s/Mercury Cougar XR7’s of the same vintage and thought they should have outsold the Ford personal luxury coupes, the Chrysler Cordoba was okay but loved the slanted front end of the Dodge Mirada’s.
The Magnum had true “beautiful brute” styling in the Mopar tradition. The Mirada was nice, but not as aggressive. I really like the blue on parchment interior colour in the Mirada ad. Glad to see Chrysler bringing that back in the refreshed 2015 300.
Both of these cars inhabited my late high school-early college years dreams. I was never a big fan of the post 1975 Charger, as it looked like the Cordoba’s poor cousin. The original Cordoba was a great looking & driving car, and I’m sure the 1975-77 Charger would have been similar. But when the Magnum came out, wow! I loved the “hidden” headlights with the clear covers and the overall “sporty brougham” styling that spoke to me. As I was in high school then, I didn’t have the money to buy one of those; during that time I was riding around in my HS girlfriend’s Dodge Dart mostly. Or her dad’s Newport. The Newport had a lot more “stretch out” room…
I liked the sheer styling of the Mirada also, but my future father-in-law had one as a company car back in the day. He had just given back his R-body St. Regis which he thoroughly hated and ended up with a Slant Six Mirada as it’s replacement. I think generally the car was OK for him, but he constantly complained that it was slow and not *that* good on fuel mileage. While I never owned one, his opinion kind of kept me away from them. Besides, I had to spend a small fortune on a certain turbocharged Mercury Capri to see why he hated early 1980’s cars so much…
Probably about 20 years ago, I ran across (IIRC) a 1980 triple white Dodge Mirada with the 360 in it. It was on a small indy car lot in Atlanta, and many of those were here today gone tomorrow outfits. Strike one. It was a decent 50-footer, but when you got close up you could see that it was (at the time) a 25 year old car. The body wasn’t bad, but it had 2+ decades of parking lot dings and dents. Strike two. When you got close to it, you could smell oil and gasoline emanating from it, with a pretty decent brown spot underneath it. Strike three. Too bad, the interior had survived the sun in Georgia for all that time and like I said earlier, it seemed like it had been kept in fairly decent condition. But I really didn’t want to find out what that brown spot was underneath it. It may have taken more money than it was worth to get it to a decent state.
At the time, I still had one of my own COALs and a couple of toddlers, so a two door personal coupe would not have been a wise choice anyway. I really should have been looking for something more practical. Like a minivan. Or an extended cab pickup truck…
I’d love to have seen the Magnum front clip on the wagon body shell, the cheap way to have made a Dodge St. Regis wagon and keep a toehold in the big-wagon market until the T115 minivans were ready.
Re pic #4
I think I hear banjos!
I’ve always liked the Magnum, but I’ve always *loved* the Mirada. Just really like the angular styling, with the Cord-esque grille, the sharply pointed fenders, the interesting roofline…just really good-looking cars to me. Give me one with a 360, no vinyl roof, the factory alloys, and the dark/light interior like in that brochure picture, and I could be quite happy. It’s a car I hope to own at some point, though they’re rare enough that it might always remain a pipe dream! The related Cordoba certainly isn’t bad but the more blunt front end doesn’t do it for me like the Mirada does.
Hmmmm, maybe if it had a four-door running mate, it would have sold better.
That’s a good point. It certainly would have been competitive against the likes of the LeMans, Cutlass, and Cougar. At first I guessed maybe Chrysler wouldn’t have wanted to cannibalize sales…but from what? As it turns out, nothing. The St. Regis was much bigger and was axed after ’81, and the Diplomat was always a fleet/police special, with relatively few civilian sales after the ’80 restyle. (They tried to take back some of the civilian market with the 5th avenue clone SE, but that wasn’t until ’84.) The 600 didn’t come along until ’83, around the same time the Mirada was going out of production.
The only sensible answers are either a)not enough development budget or b)Chrysler’s damaged brand image at the time. Very few folks bought the Mirada coupes and I don’t think it was on account of the styling, or even necessarily the performance–probably in large part due to the fear that Chrysler would go under for good.