Late 80s Hot Hatches; I think I'll go with the Peugeot 205 GTI, but that Fiesta is a close second.
1970 Dodge Challenger R/T vs 2008 Dodge Challenger SRT-8; Without a doubt, the Challenger R/T.
Ferrari 458 Italia vs Lamborghini Gallardo LP570-4 SL; I would easily pick the Gallardo over the Ferrari. I absolutely adore all Gallardos.
Aston Martin Vanquish vs Bentley Continental GT; The Vanquish for looking better than the Bentley and I kinda prefer V12s over W12s.
Jaguar XKR-S GT vs Aston Martin V12 Vantage S; V12 Vantage S please!
Audi R8 5.2 FSI vs Porsche 911 Turbo 997.2; Porsche 911 Turbo, thought I will note that I also love the Audi R8 very much.
GT-R Generations; The R32 Skyline GT-R easily, that's my favorite Skyline GT-R out of all of them.
"Worst" Cars; I'm going to simply pick the Chevrolet Vega.
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2015 Ford Mustang GT Performance Package
or
2014 Chevrolet Camaro SS 1LE
I personally would immediately go with the Mustang. I know that on Motor Trend, the Camaro was a bit faster around the course, but I still prefer the Mustang. It's still a great track performer, it looks great imo, it has a larger trunk opening, and unlike the Camaro; you can actually see out of it.