Thanks for the replies.
I had seen the 7'10'' advertised but I thought that was probably a flat on the floor dimension, I was hoping i might be able to squeeze in the extra 8'' by putting it up diagonally on the dash. I guess i will just bring it to a dealership and test (hey, can i put this wax-covered board in your car?)
Also, I am wondering whether to pop for the "sport" option. What else does it get you besides the wheels and body trim?