I would really like if the racetracks would have 2 lines. Like slot car racing. You need an open line to pass someone. (Like a 2-lane road with 2 trucks going the same speed, a car behind them can't pass by magically teleporting through them.) That way it is more realistic on the overtaking a vehicle. Each line could even have a slight timing difference.
The ideal race line would be using a combination of the 2 lines throughout the lap. A faster car could pass on the "slow" line but would be at a slight disadvantage. The faster car should eventually make the pass on the other line, instead of the current version of "ghosting" through the car in front of him.
This is my biggest hope for this game, instead of everyone driving the same line and going through each other like phantom cars. This would be the simplest way to add accidents/crashs as well.
If 2 cars use the same line at the same time. Boom! Accident/crash just occurred. (Got more ideas on this subject, will add in separate post.)