"Ariel announce the latest version of the Atom - the Ariel Atom 500, powered by a small V8 engine. With over 500bhp in a 500kilo package the Atom 500 will boast one of the highest power to weight ratios ever for a production car, ever. At over 1000bhp per tonne the Atom 500 will be the ultimate statement in performance and is destined to be made in a limited edition."
http://www.arielatom.com/specs/atom-500-v8
This is the ultimate track toy (non-F1) and is street legal.
btw this is the Top Gear with the original Supercharged Ariel Atom:
and this is some one trying it out on a street:
1:20 - 1:40
Not really comparable to any conventional car, but I still think that this will be the most fun to drive.