1973 Chevrolet Corvette XP 897 GT Two Rotor Concept road test

Paul Harmer

Another place, another time. Unique Rotary Corvette Concept car that escaped from Chevrolet. Corvette Two Rotor. Three GM bosses sought to reinvent the Corvette and the mid-engined Two Rotor was the result. Mark Hales tracks down a unique survivor. Photography Paul Harmer.


The Corvette is America’s only home-grown sports car. Now, 65 years up the road, it still features a separate chassis and a plastic body and it still has a large V8 engine in the front, driving the rear wheels. It’s a kind of Stars and Stripes statement, a bit like NASCAR. A set of traditional values that represents everything about a brand. If the rumours are correct, the Corvette’s engine might finally be about to move – but it won’t be the first attempt at revolution.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept  road test

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept road test

The 1960s and ’70s saw giant personalities heading up the big car corporations and directing the next model range was a good measure of influence. The other essential was to do so for less money. There are many players in a story that began at the end of the ’60s but three stand above the parapet. Russian-born maverick Zora Arkus Duntov had risen through the US motor industry to become an engineer at GM in the early 1950s, responsible for most of the Corvette’s development. He was convinced that the next Corvette should have a mid-mounted engine.

A flamboyant John Z DeLorean had also begun as an engineer, becoming the youngest-ever head of a GM division – Pontiac – and taking over at Chevrolet in 1969. He was keen to have a new Corvette as an early mark of his leadership.

Ed Cole was the biggest of the three beasts, another engineer, beginning his career at GM in the 1930s, becoming chief engineer in 1946, then GM President in 1967. The Corvette of 1953 was his project, as was the introduction of the small-block V8 engine in 1955. Later, he would push through the illfated air-cooled, rear-engined Corvair, which earned him a controversial reputation but also suggested to creatives like Duntov that he was open to new ideas. This was a good time for Cole to lay the Corvair’s ghost to rest and have one final significant influence on the automobile. Mid-engined or otherwise, it was clear to all that it had to be lighter, more fuel-efficient and cleaner.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept road test

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept road test

Felix Wankel’s inspiration for the rotary dates back as far as 1929 so it had already endured a long gestation, but by the late 1960s it looked as if its time had finally come. More than 20 companies worldwide bought licences from Wankel GmbH and German carmaker NSU, which was an early champion.

In America that included Ford, Chrysler, AMC and GM – all via aviation and industrial giant Curtiss-Wright, which had acquired the rotary’s rights for the US. Perhaps surprisingly for a company regarded as the ultimate conservative, only GM saw some advantages: emissions legislation was a growing reality and at first it looked as if the rotary’s very high exhaust temperatures would be helpful in meeting the new rules.

More important to a company that had eschewed front-wheel drive and radial tyres because they added a few dollars to manufacture, the Wankel had fewer than half a piston engine’s moving parts, so it might be cheaper to produce. And it was extremely compact, so a smaller car could offer similar space inside, and it could be lighter: according to GM’s engineers, crash legislation and emissions equipment could add 270kg to a car – or 1mpg less. There was the modular aspect too: add more rotors to get more power but use parts you are already making. Automation and standardisation were company watchwords.

Having looked at buying Wankel GmbH outright, in November 1970 Cole instead agreed to pay $50 million for production rights. It was a bargain in GM terms and his grand plan was that the GM of the future would be all-Wankel. Cole had enough power to see his rotary plan become reality, and the problems that he and his engineers knew about (and took Mazda so long to fix) would surely be easy for a giant like GM.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept road test

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept road test

The volume Vega model was to be the first recipient of GM’s RCE – as in Rotary Combustion Engine, for the Wankel name was taboo – which featured two rotors, each with three combustion chambers and equivalent to a total chamber volume of 6538cc, according to the way GM measured it. Power was 180bhp, low for such capacity but in line with what the European Wankels were achieving, even if their nominal volumes were a lot smaller. In the end, GM declared the capacity as 266ci, or 4362cc.

The development of the Corvette replacement – the ‘Two Rotor’ – went in parallel with the Vega’s and it was to be Eurosized, partly to perform on the available power but also to meet Cole’s new spacesaving initiative. The stylists chose a midengine layout mainly because it could use the engine and transmission package destined for the front-wheel-drive volume models.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept engine

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept engine. Above and facing page Mazda 13B engine in place of the GM RCE – either leaves a lot of boot space behind. Two Rotor is remarkably original throughout; even the original radio still plays longwave, and note the Wankel logo in the centre of the wheel.

GM was flat-out with the saloons so design and production of a suitable Corvette chassis fell to Duntov’s Corvette Group, which was also short of both staff and time. The answer was simple, and logical. If the new car was to be Euro-sized then start with some borrowed Euro underpinnings.

A mid-engined Porsche 914/6 was acquired and its chassis shortened to reduce wheelbase by 6.5 inches. The Porsche strut front and semi-trailing arm rear suspension were retained – as were the brakes – but the mounting points were moved, widening the track by 3in at the front, 1½in at the rear. A two-rotor engine was installed, driving a three-speed auto transmission from the GM range, leaving plenty of room for a four-speed manual, and more rotors.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

The chassis modifications were completed in record time, and by mid-1971 the studio had created a fresh and modern body shape. The green light was given to build a working prototype, and a brutal June ’1972 deadline to present to the top men.

So there was no alternative but to get someone else to build a body, and in January the rolling chassis and body buck were shipped to Pininfarina in Turin, a location that has implications for our story.

Pininfarina completed a steel body – though the styling was all the GM studio’s own work – in a record 12 weeks and the car was freighted back to America for fitting out. A little over a year later, in October 1973, the Two Rotor – as it was by then officially known – was a major hit at the Paris Salon. However, the reaction of potential buyers – the Corvette faithful – was less enthusiastic.

Crash structures had ensured that the car was heavy despite its size and it only went as well as 180bhp could propel it. I suspect the fact that it didn’t look or sound like a Corvette also had something to do with it. But then outside events took a hand. The oil crisis hit the world and, for a while, fuel economy became more important than emissions and the Wankel’s thirst was an even bigger problem for a car that didn’t go.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

Duntov’s four-rotor of 1973 was a yet more dramatic attempt that did go, but unsurprisingly consumed twice as much fuel. And then DeLorean was moved sideways to the commercial division and Ed Cole retired. The rotary and the mid-engine lost their champions and the revolution was over.

GM would have promptly crushed the Two Rotor prototype, not least because a complete set of Porsche underpinnings might have proved an embarrassing revelation for a company that ‘could do anything it wanted’, but there was a snag.

The bill from Pininfarina had been considerable so, to avoid duty when the car returned to the US for fitting out, it had become a ‘temporary import’. The only way to avoid another bill was to send it back to somewhere in Europe. That turned out to be up in the roof at Vauxhall, GM’s outpost in Luton, Bedfordshire, where it sat in its crate for ten years until an office expansion brought another brush with the scrapman.


How these large companies can be so dispassionate about their significant history is beyond me but, with just hours to go before the jaws closed, Englishman Tom Falconer – arch enthusiast for all things Corvette – received a phone call from Geoff Lawson. The then-designer at Vauxhall, later head of styling at Jaguar, thought Tom might like, as an office ornament, a metal cube that represented a $50-million investment.

He certainly didn’t want the ornament: he wanted the whole car, but Lawson didn’t have that authority. ‘You’ll have to talk to Chuck. He’s the only man who can say yes.’ Falconer is by nature modest but, crucially, during his many visits to the Corvette’s shrines he had made plenty of friends in high places, among them head of styling Chuck Jordan, about whose Cadillac Seville Tom had written a book. ‘He had enormous power,’ says Tom; ‘he was one of a very few men who could say yes and nobody would argue with him.’ Jordan had also famously once asserted that no Corvette would ever have a steel body, or a mid-mounted engine.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

Tom got through to Chuck and managed to charm him. ‘Hell, what d’you want that thing for? It has no engine, and no transaxle.’ What had once been the harbinger of GM’s new dawn was duly loaded onto a trailer behind a Citroën estate car and transported to Tom’s premises in Newcastle, where it again sat for a while before featuring a Vauxhall Cavalier engine and three-speed auto gearbox in an early attempt to make it driveable, then, in an ironic twist, a two-rotor Mazda engine. The Mazda mounts the opposite way round, so the exhaust ports are on the wrong side, and the crank turns the other way, which obliged Tom to design and install a transfer gearbox. But the car drives, and does so with a two-rotor engine – which will do for the moment.

The story doesn’t end there though. All the known RCEs had been zealously gathered and scrapped – save for one that survives in a museum at Ypsilanti. The engine’s internal details had been as secret as GM could make them – it was not a Wankel, remember – and it wanted to control the legacy, a difficult task in a country the size of America, especially when every assembly plant had been required to have an engine on prominent display.

Years later, Tom’s network threw up another piece of serendipity. Someone knew of a genuine RCE engine that one of the plants had donated to a university, and one of its lecturers had taken it home. ‘He wanted too much money for it,’ says Tom, ‘but with the passage of time, he became more realistic.’

In October 2017 the engine was loaded into a crate and shipped to Tom’s workshop, now in Snodland, Kent. There’s a bit of work to do but, from what I know of Tom Falconer, his Two Rotor will once again feature a GM rotary, and it will be the only one.

It’s too easy to blame emissions and the fuel crisis for the Two Rotor’s demise, but it’s more complex than that. Fuel economy wasn’t the most important thing at the beginning of the 1970s; only with the fuel crisis did it move to the top of the list, and America could have so easily embraced the diesel like much of the rest of the world, but it didn’t. GM could have made a smallerengined Corvette, but it didn’t. DeLorean left GM in 1973 and set about trying to buy the Two Rotor project for his eponymous car company, to build the ‘World Car’ he’d envisaged. Predictably, the parties couldn’t agree, so DeLorean did his own mid-engined thing using a Renault V6.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

The sense of what might have been is frustrating. The Two Rotor is undeniably handsome as well as innovative and there’s no doubt it left its mark – as Tom wryly observes, ‘…after it had featured in Style Auto in 1976. Well, every car designer reads that’.

The front end of the new Vega inherited the headlight set-up, and the Pontiac Fiero – ironically the only mid-engined American car to be made in volume – took the nose shape. And can we see the rounded door windows and rear aspect on Porsche’s 928? Meanwhile, Mazda went on to prove that the rotary could be cleaned up and sorted out and that a car of the Two Rotor’s size with rotary power could be a success, even an icon. GM could so easily have badged it as something other than a Corvette but, without Cole and DeLorean, the establishment prevailed and the Corvette went back to the front-engined future.

There are so many details that strike you about Tom’s Two Rotor. Its condition for one, not to mention originality. Other than the engine, absolutely everything is as it was when it left America all those years ago, even down to the motor show ’plates, the original space-saver spare wheel and tyre, and all the original air conditioning equipment. The underbonnet still has that matt black big-manufacturer production look about it rather than that of a special with welded-up brackets and bright blue hoses. And just look at the original data plate, which acknowledges ‘The builders and craftsmen of Chevrolet Mock Up dept.’ Even the original radio works. There are the smaller styling details too.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept driven

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept . Facing page and right Clay model in GM’s studio led by design chief Bill Mitchell, next to the real steel thing; badging tells the tale of a car that – officially – was not powered by a Wankel engine. Above and left The prototype with three men who shaped it: from left, Henry Haga, John Wasenko and Otto Soeding. Cover story in R&T asked the important question.

The reverse cleavage in the screen that meets the one in the bonnet was one of design chief Bill Mitchell’s tics, harking back to his formative years in the 1930s. It’s a dual manufacturing and optical nightmare, and obliges a wacky wiper system that sweeps outwards from the centre, operated by huge cantilever arms just in front of the firewall. And there’s the three-headlamp system that was to be universal across the range, still complete with its spirit-level adjuster.

The overall impression, though, is much more European than 1970s American. Was that really in DeLorean and the designer’s minds? A brief for a world car? The Corvette had never sold in the UK because it was left-hand drive. This would be easier to engineer. We will never know.

It squats on a set of handsome goldpainted very American Racing wheels that, together with the red paint finish, Tom reckons was a nod to Ferrari. When Tom collected the car, it still wore the original 205/60×16 tyres. ‘We heard a bang one day and went into the shop to find one had burst all on its own.’ Also striking is how low the car sits, despite riding high on relatively soft suspension. The roof measures only 42in from the ground, not quite a GT40 but 5in lower than the 914 on which it’s based.

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept interior

1973 Chevrolet Corvette XP 897 GT Two Rotor Concept interior

The Wankel engine’s compact dimensions and rear location clearly allowed designers additional freedoms with transmission and driveshaft heights as well as elegant proportions, without a weight penalty right at the rear. And the doors are simply huge.

You can pretty much sit in sideways and swing in your legs in the modern supercar fashion. There you find excellent visibility over the sloping nose and a spacious lay-back driving position with vast legroom.

The seat doesn’t adjust but the pedalbox does, like a LaFerrari (or 1960s Marcos), and the steering wheel is reach-adjustable. Dials are buried in deep holes, a GM fashion of the time, and things that seem like gimmicks are logical given the cutaway dash: the lights and wiper switches fall easily to hand in the door.

I’ve complained so often how it’s impossible to find a car that is mechanically as it was, but other than the engine this is about as close as it gets. The Mazda substitute is certainly noisy – keeping a Wankel quiet is another rotary challenge – but, once moving, the suspension is compliant, which is not quite the same thing as soft; it moves about as you drive, which is another characteristic we miss these days, when big weights have to be firmly controlled.


Move the wheel and there’s a response that comes via the seat as well as the wheel’s rim and your sightline, something I used to describe as ‘involving’ and which most often came from small masses concentrated near the car’s centre. The latter is true here, but the car certainly isn’t light. It rolls quite a lot too, as you can see in the pictures, yet it doesn’t aggressively dip and squat, staying nicely flat while riding well. The steering is unassisted so it’s quite heavy but it’s direct and informative. Edge a bit too quick into a turn and add a bit more, and the car turns a bit more. Lose a bit of grip and the message is there at your fingertips.

But… The car impresses for its nice, easy balance and its layout, its looks and the amount of space for luggage behind the engine as well as occupants in the cabin. It’s also sophisticated, at least potentially.

However, it doesn’t challenge and excite and it’s difficult to see how it could. The Mazda engine is probably pushing out about 120bhp, or 60 less than GM’s would, but some of 180bhp would still get lost with three gears and a lazy torque converter, which a big V8 can overlook.

The last Corvettes I drove would spin-up an inside wheel on a roundabout at will; such things are not a measure of a car’s excellence, but they are a statement of intent. The Two Rotor would have undergone some refinement, and, as Mazda was able to show, it would have been possible to extract more power from the existing engine, or it could have acquired some more rotors.

It’s a huge shame the Two Rotor didn’t go into production, but it probably carried too much weight of expectation at the wrong time. As someone said, if they’d spent a fraction of the amount spent on gas turbines, the rotary would have been sorted long ago. How about we just go back in time, call it something else, and see what happens?


How useful was this post?

Click on a star to rate it!

Average rating 5 / 5. Vote count: 2

No votes so far! Be the first to rate this post.

Additional Info
  • Year: 1973
  • Engine: Wankel type petrol Two Rotor / Mazda 13B build
  • Power: 180bhp at 9800rpm
  • Torque: 110lb ft at 7800rpm