Toyota gr b (probably many other cars...) with nitro and good settings for transmission in order to have a good start and last speed blinking at the end of the 1000m
Pretty sure I did it with the R32 GTR, after spending lots of time tuning gear ratios, reducing downforce, perfect ride height etc etc… and of course a bit of Nitrous 😁
The same car did consistent 8s in the shorter (0-400m) events.