F1 for sure. No contest. Ground effects, extremely low center of gravity, yet similar or better power-to-weight ratio to a bike pay off.
HOWEVER, when the discussion turns to street vehicles (as it has in this thread), it can more often than not be a reverse situation.
Typical sport bikes are much closer to their racing bretheren than a car (even the Viper). As an example, with my relatively heavy more sport-touring bike (1990 ZX-11) and my normal street setup, I see lap times in the 1 min 43 sec range at Laguna Seca, and can often see speeds in the 140 - 150 mph range between turns 11 and 2. However, even with competition-level tires and brake pads on the Viper (Hoosier R3S03), best I can do at Laguna Seca in the Viper is around 1:49, and barely top 125mph max speed before ******* the brakes for turn 2.
Comparing peak power to weight is clumsy at best, but still points out some differences; Power output on the bike is around 130 hp at the rear wheels - so, 550lbs for the bike and 200lbs for me somes at to 0.173 hp/lb (and at least five current bikes are lighter and have higher horsepower). Compared to the Gen II's 450 crank hp which works out to around 390rwhp, and my RT/10's 3400 lb plus my 200 lbs; 390/3600 = 0.108 hp/lb, and thus the acceleration difference is still quite significant. The car can carry more speed through turns due to lower center of gravity, at least in my case, as I'm not much of a knee dragger, but the bike will out-accelerate the vast majority of cars out there.
Then, there's the not-inconsequential issue of driver. One of our NorCal club members routinely gets around 1:40 at Laguna Seca with a 1996 GTS whose only modifications are brake pads, brake fluid, and tires - absolutely zero engine or suspension work (I've been to dyno days with him). He's just got the years of SCCA racing to know what he's doing better than most others. So, in his Viper, he can beat me on my bike, and is routinely about 13 seconds faster than I am in my Viper, and I am, believe it or not, faster than many others.