Oh, we hardly race on weekends. Mostly on Wednesday or Thursday nights.
With online play you can use any car in your garage so yes, anything you have built up is allowed. Actually its more fun when you do as you get to truly test your setups against other human racers.
Sure there is some bumper and doors touching on the smaller tracks or through the corners, its fun but I raced people that have no idea that those signs on the side of the road indicate how far the corner is and then next thing I know I'm into the overrun, wall or out of the race.
We have had some great accidents because this is racing and it happens. Check this one out....CTS-V gets some major oversteer through the corner and he can't correct. I'm coming through very fast an no time to brake or avoid. It happens.
Of course, drifting through the corners together is something else. This was from a race, not us trying to drift, just happened.