From what I have heard from my fellow more experienced players, there is the issue of a little unbalance in D class, mainly with the Cadrona and Emperor, which are regarded as beign the absolute best cars. Also the Previon is regarded as beign the worst car (Altrough I haven't driven any of them), so it would be good to balance the cars but make them...different but performing the same with a good driver if you get what I am trying to say
D class has already been balanced. Every car should have similar map times, but it depends on player's skills, latency, whatever. There's no best or worst car.
To be honest we can't make perfect balance. The major difference between cars is how difficult to drive they are. Each car will perform differently depending on race type. We can make each car harder/easier to drive but that's about everything. Skill sometimes plays a big role in this, as some cars are difficult to drive but that's being hidden by some people who are very experienced racers.
Yeah, I was just listening to what people said without actually experimenting myself, I just bought the Emperor and its kinda meeeeh for a stock car xD