I've never tried it in a car, but when I was a kid we used to pour all kinds of things into our old go-carts, just to see what would happen. I do remember paint thinner being one of the things that made the engine run so well we blew it up. But of course these were very small >10hp Briggs and Straton lawn-mower engines.

We also got a couple of my friends grandads nitro pills and dropped them in the tank, believe it or not it made it run better too, believe that one blew also.

But it'd be worth trying if done properly, I do remember it bein some serious extra kick in teh butt in that cart.

I may give it a shot tomorrow and see how it goes, I'm pretty sure I have 3-4 gallons in the basement. And I only run 93 octane in it, so I should be able to get a nice octane rating easily.