Buick built 34,080 Rivieras for 1973, the last year of the flamboyant and controversial “Boattail” design. Only 1,234 of those had the high-output Stage 1 engine, and only a few of those had Buick’s pioneering “MaxTrac” electronic traction control system, introduced 20 years before traction control became commonplace. Let’s take a look at a coupe of 1973 Rivieras with these options, and see how they worked.
The story of the 1971–1973 Boattail Riviera has been told on CC before, but a recap may be in order: This was one of former GM Styling VP Bill Mitchell’s retro-’30s ego trips, designed by the late Jerry Hirshberg, a Buick stylist who went on to a long career designing other definitely-an-acquired-taste cars for Nissan, like the must’ve-seemed-like-a-good-idea-at-the-time Pulsar NX and the Jaguar-baiting oddball Leopard J. Ferie (sold on this side of the Pacific as the Infiniti J30 sedan).
Mitchell wanted the Boattail, Buick general manager Lee Mays definitely didn’t, and GM president Ed Cole threw a wrench in the works by demanding that the car share some structure and glass with the Buick LeSabre to save money. So, the original design was embiggened and watered down, which made no one happy. Hirshberg later called this “one of the more painful exercises I’ve ever been through,” and admitted that the finished car “looked slightly eccentric.”
Some people loved the Boattail Riviera anyway, because it was different; some people hated it, because it was different. For better or worse, there wasn’t much like it on the road in the early ’70s. The Boattail was completely at odds with contemporary trends in personal luxury car design, but it still ended up selling reasonably well: 101,618 units in three model years.
However, federal safety standards posed a problem: Motor Vehicle Safety Standard No. 215, effective September 1, 1972, required new cars to be able to absorb a 5-mph front impact and a 2.5-mph rear impact with no damage to lamps, reflectors, fuel system, cooling system, or exhaust, and the hood and trunk had to remain openable afterward. The shape of the 1971–1972 Riviera “stinger” made the last point a headache.
So, the boat’s tail was bobbed a bit for 1973, and the front bumper was beefed up with hydraulic energy-absorbing struts.
You could argue that the bumper changes further compromised an already-compromised design, but that particular seagoing vessel had long since sailed by the time the first Boattail Riviera went on sale in late 1970. The revised bumpers did add weight (up 143 lb from 1972), the last thing the already enormous Riviera needed.
The Riviera had always cultivated a kind of “gentleman’s GT” image, and you could still order one that way for 1973 if you were so inclined. Spending an extra $171 would get you the GS handling package, which gave you a “radial roadability suspension” with HR70-15 tires, firmer springs and shocks, and a rear anti-roll bar. The number of Riviera buyers interested in that sort of thing was never very great — the take rate on the GS package was typically around 10 percent — so Buick kept softening the GS suspension in hopes of making it more broadly appealing. Even so, only 3,933 1973 Riviera buyers ordered it, and buff book reviewers groused that the Riviera GS wasn’t what it once was.
For another $139, you could add the Stage 1 option, which gave you a higher-output version of the Buick 455-cid V-8, plus a 3.23 performance axle and “positive traction” (limited-slip) differential. This being 1973, with compression ratios falling and add-on emissions controls proliferating, “higher-output” meant an additional 10 hp and 5 lb-ft of torque, for a total of 260 hp and 380 lb-ft.
These were SAE net ratings, so the 1973 Riviera Stage 1 wasn’t quite so far behind the 300+ hp gross ratings of Rivieras past as it looked on paper, but this was no longer 1967, and those 260 hp were now contending with close to 5,000 lb of semi-fastback grandiosity. CARS magazine tried a 1973 Riviera GS Stage 1 and managed 0 to 60 mph in 9.2 seconds, running the quarter mile in 15.65 seconds at 88 mph — okay, but not the stuff of Woodward Avenue drag racing legend. CARS also warned that trying to replicate that performance required such a heavy throttle foot that fuel economy would dip into the single digits. Unsurprisingly, 96 percent of Riviera buyers were content with the standard engine and its taller 2.93 axle ratio. Ho hum.
Although these cars might not have had startling acceleration even with the Stage 1 engine, they DID offer a most interesting and sophisticated option. Notice the switch marked “MAX TRAC,” indicated by the green arrow? That signifies the presence of the $89 MaxTrac electronic traction control system.
Traction control has been common on modern cars for quite a while, proliferating in the ’90s as antilock brakes became more widely available on cheaper cars. However, Buick first offered MaxTrac in 1971 — I think it might have been the first system of its kind in regular production.
Like most ’70s electronics, MaxTrac was a little crude, but the basic idea was the same as modern traction control: Wheel-speed sensors detected when the drive wheels were slipping, and an electronic controller automatically reduce engine power until traction was restored, preventing wheelspin and fishtailing on slippery surfaces.
On modern cars, traction control typically uses the same wheel speed sensors as the antilock braking system. Although GM had an electronic rear-wheel antilock system in this period, available on the Oldsmobile Toronado and some Cadillacs, Buick didn’t offer that system, so MaxTrac had its own sensors: one in the left front wheel hub, tucked inside the disc brake rotor, and the other on the transmission, driven off the speedometer gear.
Each of those sensors produced a voltage proportional to speed. A solid-state electronic controller in the dashboard then compared those voltages to determine the relative speeds of the front and rear wheels. If the sensors indicated that that the drive wheels were turning more than 10 percent faster than the front wheel, indicating that the drive wheels were slipping, a pulse converter and power transistor would inhibit the current flow to the ignition system, reducing engine power.
The more the wheels slipped, the more the power would be reduced; power would then be gradually restored as the front and rear wheel speeds equalized.
Buick didn’t intend MaxTrac to substitute for a limited-slip differential, and recommended combining the two for best traction on wet pavement, snow, or ice:
| Road Condition | Standard Axle | Positive Traction Axle | MaxTrac | MaxTrac With Positive Traction Axle |
|---|---|---|---|---|
| Dry pavement | Std. | Same | Same | Same |
| Gravel, wet asphalt, hard pack snow, ice | Std. | Good | Better | Best |
| Heavy snow or mud; trailer pulling | Std. | Better | Good | Best |
| Stuck in snow or mud (rocking) | Std. | Best | Poor | Poor |
The main drawback was that if the drive wheels were actually stuck in mud or snow, MaxTrac would make it very difficult to rock them free. Buick recommended turning the system off in those cases — a nuance that I assume was lost on most owners. You also needed to turn MaxTrac off for dragstrip-type acceleration, although Riviera owners mostly didn’t do that.
Although MaxTrac was first introduced on the Riviera, by 1972, it was optional on any full-size Buick. I don’t have any installation figures, but I don’t think it was ordered very often. For the most part, Buick buyers didn’t even order limited-slip differentials, so wet-weather traction doesn’t seem to have been a big priority. MaxTrac was also complicated enough that I suspect a lot of customers would have needed a demonstration to understand what it was supposed to do, much less decide if it was worth the extra money. Riviera buyers were more interested in luxury options like automatic climate control or a power sunroof, a new option for 1972.
Both the Burgundy and Midnight Gray 1973 Rivieras pictured here are equipped with MaxTrac, although for whatever reason, the Mecum listing for the gray car doesn’t even mention it. I would have overlooked it completely if the switch hadn’t been visible in one of the dashboard photos — a weird oversight for a rare and interesting option. I don’t know if MaxTrac is worth any kind of premium, but it is certainly a talking point.
Both of these well-optioned Rivieras originally stickered for over $8,000 (a relative worth of around $65,000 in 2025).
The Stage 1 and MaxTrac options returned for 1974, their last year. (The Burgundy 1974 Riviera pictured above has the GS option and the Stage 1 engine, now rated at 245 hp, but not MaxTrac.) However, both the Boattail and the thrill were gone. Sales plunged by 40 percent, and while part of that was undoubtedly due to the 1973–1974 OPEC embargo, 1975–1976 sales were no better, suggesting that avoiding controversy did Riviera sales no favors. It would be another five years before the Riv would again be worth paying attention to except for loyalists.
MaxTrac appears to have been dropped for 1975. The conventional wisdom is that its ignition voltage twiddling wouldn’t pass muster with the latest emissions standards, which is plausible, but it’s also possible Buick just decided there wasn’t enough demand. By the time traction control made a comeback, most of the cars offering it had digital engine computers with feedback control, which handled the emissions issue, and ABS, which enabled traction control to be offered at only a modest extra cost. (Saturn, for instance, packaged traction control with ABS on automatic SL and SC models for only $55 more than ABS alone on stick-shift cars.)
There’s a pretty good chance you made up your mind about the styling of the Boattail Riviera before you even clicked the read-more link, and I’m not going to try to change your mind one way or the other. In any case, enough people seem to like these cars that their survival rates are pretty good, and prices are high enough to encourage owners to take good care of them. The Midnight Gray car sold for $28,600 in November 2025, while the Burgundy ’73 sold for $45,100 back in July 2020.
These Rivieras are still unusual enough that bystanders tend to stare and little kids tend to ask, “Daddy, what’s that car?” If you enjoy a little notoriety, they might be just the thing, but remember: If you decide to amuse your curious audience with a tire-smoking burnout, just make sure you first click the MaxTrac switch to “OFF.”
Related Reading
Curbside Classic: 1971 Buick Riviera – Bill Mitchell’s Pointy Dead-End (by Paul N)
Curbside Classic: 1972 Buick Riviera Boattail – Swan Song Or Big Ugly Duck? (by Paul N)
Curbside Classic: 1973 Buick Riviera GS – Be Memorable (by Joseph Dennis)
Beauty is in the eye of the beholder, but I think that the rear three-quarters view of the Boattail is gorgeous. Certainly one of the most unique designs of a mass produced car of the era, unfortunately let down by a front end that is in-cohesive and quite bland. Pity because the ’68s and ’69s had a more interesting front
Thanks for the article, I had never read much about max-trac – I was aware of it’s existence but not how it was engineered. If I read it correctly, there was no control loop on fuel flow; regulating only the ignition would result in non-optimal combustion; this could explain the concerns about regulations.
I was reading every new car brochure I could get my hands on in those days, and I must not have been paying attention because I do not remember either the Max Trac or the Stage 1 availability at all. I was probably paying more attention to some other cars, because Buicks of that time were not of much interest to me.
I liked the brashness of the boattail when it was new, and I still do. I don’t think it is beautiful, and I don’t think it looks great from every angle, but I like it when someone goes off on a styling riff and something unusual comes out. What will take me out of the mainstream here is that I think the 74 restyle actually came off quite well. That big drop in sales might be mostly attributable to going from a record breaking sales year for the industry (1973) to one of the worst (1974).
Another reason they dropped it in ’75 might be related to the new Catalytic Converter. Cutting the ignition would run the risk of dumping raw gas into it.
Incompatibility with catalytic converters might have been a reason for dropping it, but it wasn’t going to dump raw gas into the exhaust. The ignition is not cut per se; the controller alters the ignition duty cycle when it detects slip. I added another graph that illustrates that.
I’ve always had a thing for the boat tail Riv. That burgundy with the GS trim and Buick road wheels is perfect. I may be outside the mainstream in that I found the tail of the ‘73 to be an improvement over the ‘stinger’. Pairing that tail with the 71-72 nose would make it perfect in my eyes.
I too like the boat tail look .
I’d never heard of this interesting option, were I still in snow country I’da been very interested .
-Nate
Controversial looks or not, the one sure non controversy is Buick’s Road Wheels. Quoting a CC contributor, “Buick’s Road Wheel would make an ox cart look good”.
I actually think the rear bumper of the 73 restyle is an improvement, the 71-72s have that same thing I find offputting about 68-69 Skylarks where the rear end is concave towards the center. The point of the Boat tail mitigates the “pre crashed” look of that design flourish at least but I just have never cared for that detail. The flattened 73 completely fixes it and in my opinion the point was unnecessary anyway, it’s not like the C2 Corvette’s boat tail had one.
Overall I would classify myself as liking the boattail, but with a genuine understanding why others do not. Being out of step with the prevailing design direction in 1971 is a GOOD thing and while it’s definitely too big and looks “off” from certain angles, based on the Riviera’s design trajectory by the 1970 model and what they later morphed the boattail into with Kady’s forgettable bustleback II think it beats any hypothetical alternative. Plus I can only be greatful something as radical as the boattail existed in a decade that ended with bland stunted boxes on wheels… (even though the excesses of the the Boattail and others are partly what led to that reset).
I checked the picture showing the “MaxTrac” option on the dashboard and if you check carefully the speedometer. It shows km/h instead of MPH which make me wonder if that Riviera have once put its wheels in overseas market?
That hadn’t registered to me, but there’s another photo of the speedometer in the listing, and you’re right, it’s metric. The auction listing offers no explanation of this, makes no mention of MaxTrac, doesn’t explain why the car has an exterior/interior color combination that I don’t think was normally available, and incorrectly claims the car has leather upholstery, so it’s unfortunately not very revealing on any of these points.
Here’s an option that you would have to be seriously into minutiae to even be aware of, much less order. I’m not surprised that it was ordered so infrequently. I don’t think it’s the sort of thing that most salesmen would have been aware of, or suggested to a customer.
GM (and sometimes the other US automakers) seemed to have quite a few safety-related options on their big cars in the early-mid ’70s that weren’t heavily promoted or explained to prospective customers. The dual front airbags available from ’74-76 were in this category as well as early versions of traction control and antilock brakes. These were all quietly dropped by the late ’70s, with almost none of the automotive or consumer press noting their discontinuation.
Thank you for including the control systems diagram for Max Trac. At first I guessed they may have retarded the timing, but the brute force method of cutting the ignition is simple and effective.
If thus was something Buick developed rather than simply purchasing, they probably did not recover their investment. A sad fate for a nifty option.
I think that the ’73 rear end was better looking than the original protruding bumper. Combine the ’71 front end with the ’73 rear end would make a really nice looking car. The front impact bumper was quite unattractive, but as anyone who ever owned an early 60’s car knows, those earlier light looking bumpers did not hold up well even in minor parking lot collisions.
The personality of the Riviera changed quite a bit from the previous ’66-’70 models. These were “Gentleman’s muscle cars,” while the ’71 through ’75 were more like a Coupe de Ville. That’s how they felt to me, as I had a ’66 and a ’71. Also had a ’70 Coupe de Ville, which was pretty fast and a great road car. Unfortunately, I never got to own or drive a ’63-’65 model, but everything that I have ever read about them stated that they were really great cars.
Is it me, or is that Speedometer reading 125~ MPH, in the Photo of the “Max-track switch”?
As Stephané noted above, it’s actually metric, so it reads to 200 km/h.