In fact, not many have ever been done in any form. Here, MINI claims to attempt the first-ever "unassisted" backflip in a car--a heavily modified MINI John Cooper Works Countryman, to be exact.
So--aside from the backflip itself--what makes this attempt so special? The lack of assist. People like Rhys Millen have done automotive backflips before (sometimes miffing the landing), but with the aid of special ramps that adjust the take-off angle of the front and rear axles relative to each other, assisting the rotation necessary to achieve a backflip.
After all, it's not like you can just pull up on the steering wheel and throw your body backward like you can on a bike.
Here, we see the attempt to about the half-way point; French stunt driver Guerlain Chicherit gets the rotated most of the way around, but the video cuts short just before the landing--or the crash.
Either way, we expect to see the full video in the coming days.