How fast can a sports car go?

The fastest standard production car in the world is the SSC Ultimate Aero (1287 bhp). It goes 430 km/h (255.8 MPH Guinness verified).

Answer 2:
Actually the fastest street legal sports car in the world is the Ultima GTR - Rated by Guinness, World Records academy, Society of Automotive Engineers, and Auto Trader Digital. NOTE: Top Gear (and a few others) refuses to test either the 720 base HP or 1200 base HP car or the unlimited geared cars; "officially."
Top Gear track time was 1 minute 9.9 seconds; 6.2 seconds faster than the Ferrari Enzo FXX (a non-road legal, 1 Million dollar Formula 1 car).

• 0-60 2.6 seconds (World Record)
• 0-100 5.3 seconds (World Record)
• 30-70 1.8 seconds (World Record)
• 0-100-0 9.4 seconds (World Record)
• 100-0 3.6 seconds (World Record)
• Standing 1/4 mile 9.9 seconds @ 143 MPH
• Skidpad (200ft) 1.176g (World Record)
• 231 MPH (gear limited 720 bhp version)