This was inspired by Sean’s post about Tatra’s retirement from making road-going automobiles and what might have been.
In the last few years of the Clinton administration a sizeable grant was made to the US car builders to help them develop fuel efficient large cars. Among the goals, the companies were to aim for was to reduce fuel use to 80 mpg. We seem to be slowly getting to this although with smaller cars. GM’s response to this grant was the Precept, the appearance of which seems to me to not too unlike a Tatra. Whether this is a case of convergent evolution or actual direct inspiration, I can’t say.
The GM Precept used a formula familiar to us today although the packaging is rather inconvenient – more on that later. An Isuzu 1.3 litre, three-cylinder, direct injection turbo was located in the rear of the car where the boot should be.
That explains all the vents and meshes as the rear of the side and around the back. Having the engine in the boot allowed a sealed front end which gave the car its super-low cD of 0.16. This beat the figure of GM’s own EV1 (which I test drove once). And according to GM, the airflow through the engine bay and out of the rear apertures actually increased pressure behind the car in what is normally a high-drag, low pressure zone. The Precept also had a nearly flush undertray (Citroen did this with the DS and GS and have since forgot all about it. I had a look under a Renault Twingo and this feature is now back).
The rest of the arrangement is also now not unusual in hybrids. There is a 13 hp electric starter motor that balances the crankshaft and gearbox speeds to eliminate the need for synchros. It also boosts the engine under full acceleration. The packaging went a bit nuts at the front because here GM put in another motor, a 34 hp electric unit borrowed from the EV1 which drove the front wheels. All of this gave the precept two electric motors, a diesel motor, four coolant circuits and 16 radiators plus a battery of computing power to manage it all.
What I thought that the time (2000) was that GM could have produced a large, five-seater car that did 45 mph just by reverse engineering something like a diesel Citroen XM which got this figure in 1992. Today, I also believe GM produced this car not to show what could be done. They did it to show credulous politicians that getting 80 mpg would make for an unusable, ugly and complex vehicle.
The Detroit reactionaries tried something similar when the 5 mph crash regulations came in: girders were appended to cars, ruining their looks until the Japanese showed it could be done with no effect on cars’ aappearance at all. The same went for catalysers: these strangled American engines whereas the Japanese quickly found ways to get cleaner power.
The second offence, one of omission I suppose, is that in among the thicket of technology in the Precept lay the guts of the modern, fuel-sipping, high-miler vehicles that are re-shaping the landscape of passenger car engines. If GM had actually used half of their solution on passenger cars, starting say, in the middle of the last decade, we’d be a lot further down the road to better fuel efficiency than we are now.
Luckily for those at GM who didn’t want to bother with fuel efficiency, the whole exercise was rendered moot with the presidential election of 1999.
Had Tatra been so inclined, it might very well have seen the Precept as an inspiration that there was a lot right with the way they had been doing things all along. A modern Tatra could very well have looked a lot like the Precept and with a bit of imagination they could very well have revived their business as makers of high, tech and fuel efficient cars. Does that sound daft? It seems to me that this is precisely the niche Tesla is now occupying.