This is not such a dumb idea, not from the standpoint of the cost of fuel (diesel costs about what premium does here, especially during the winter, when you compete with the heating oil folks) but for the following reasons:
-there is more energy latent in diesel fuel- the hydrocarbons are more complex and there are more chemical bonds to provide energy from combustion
-diesel fuel is oily, so parts of the systems in a diesel engine are self-lubricating. This is one of the reasons that diesels run for longer lives, despite higher internal stresses from the higher compression ratios
-there have been a few diesel facing cars over the years- Cummins ran a few at Indy I think. There is a HUGE amount of experience with high-output diesels in offshore powerboat racing, and they are the winning combination in a lot of those races. Especially the Italian builders have done very well with them.
-modern high-speed (relatively) marine diesels are getting to the 3.5lb/hp ratio, or better. This is still far heavier than gasoline engines.
Diesels operate in a far different rev range than gas engines. High speed for a diesel is a Yanmar marine engine turning 400 revs- this is at the top of the range. 3K range is more typical. This means a whole different set of gearing choices.
Diesels produce a lot more power per unit fuel and are more economical. In racing, this means fewer fuel stops, which over a 12 or 24 hour race makes a big difference. If you can pit for fuel 2/3 of the time everyone else is doing it, you have a huge advantage.
The CAT v engine race car project above is very interesting. I don't know which CAT engine this is- they do not make a V8 over here that looks like that. It must be Perkins engine that CAT helped them hotrod. CAT recently bought Perkins, I think.
Finally, diesel horses seem to be bigger than gasoline ones, maybe because of the difference in rev range. My CAT 3116 marine engines make 350hp, but make nearly 800 ft/lbs of torque. Rev limit is 2850 under load.
Oh- they weigh about 1700 each, with transmission. Not too far from what my GT40 weighs, without its' engine. /ubbthreads/images/graemlins/grin.gif