ZZ-II has more than 600bhp, no? (I know that mine does, but it's also tuned.)
I vote Mazda Furai.
//Just as a nit-picky aside (feel free to dismiss/ignore): There's a difference between being the "fastest" and being the "quickest." For example: The fastest non-racecar in the game is the Bugatti Veyron, but with the proper setups/mods many other none-racers will beat the Veyron around a track because they are "quicker."
"Fast" relates to the highest speed you can attain (and the time it takes to get there--the Veyron is unbeatable in a straight line), while "quick" would be related to the time it takes to get from point A to point B. Now, on SSR7, there is no quicker (or faster) road car than the Veyron, but go to High Speed Ring and there might be a few challengers for that same Veyron. The Veyron will also be the "fastest" on that track, but the slowing on turns makes the other cars "quicker."
The only reason I bring all of this technicality into the convo is that you asked for the "fastest," when you might really be looking for the "quickest." Luckily, I'm pretty sure that the Furai takes both categories 👍
///Sorry about my semi-off topic tangent!
