The way the online races are set up, we use BOP, balance of performance, which adjusts weight and power so that all cars in the race are similar.
But the races we do are by category, so if it's a Gr.3 race it needs to be Gr.3 car, same with Gr.4.
Toyota, Nissan and Porsche tend to be strong all round on most tracks but for me it depends which car you feel most comfortable in.