DrifterJoeNo, but it does slightly affect performance. When racing NASCAR online at Daytona, a near-empty fuel tank makes you up to 0.150 faster per lap.
As for the slow refuelling, GT5 refuels you at exactly 2 litres per second.
About fuel and performance, check this post: www.gtplanet.net/forum/showthread.php?t=173959&page=2
SHIRAKAWA Akira made a test with a Citroen 2CV and got significant diferences!
Sent using GTPlanet for Ipad. Fantastic work Jordan!