I've got the 8" Bintel dob and it fits without a problem in my Mazda2 -- the base goes in the boot, and the OTA lays nicely across the back seats. There's left-over room in the boot, too, so I reckon I could probably put the base in the boot, fold down one of the back seats, run the OTA along that seat in to the boot, and have room for an extra passenger
