Vehicles work as expected. To test this go into the editor spawn a civ pick up truck, drive down the runway as fast as you can go and pull a hard turn, the vehicle wont flip. Now for irl test. Join the US Army, get assigned to a unit that uses the in game Oshkosh M-ATV find a long stretch of highway or runway.
Get the vehicle up to the in game max speed. Pull the hardest turn possible, count how many times you flip (this may be difficult as the driver, maybe get a friend to count for you) If the amount of rollovers does not equal what happens in game then BI probably needs to tweak a few things.