If this is the GT Cup Chilli-Pepper Race. Its easily done with a car with shortened ratios.
I used the Pennzoil GTR which probably isn't even the best. Lowered the top-speed and shortened the gear ratios and was leading by lap 2 and saw it out quite easily.
Definitely a race where the car needs setting up as the opponents are modified too (like Maggiore and the 630 Gr.4 races)