Jacked up trucks have handling problems and can't corner at any great speed. But because of the long wheel base, are not in danger of rolling end over end even with a heavy engine positioned slightly behind the front wheels. "smart" cars on the other hand, weigh very little - if memory servers two passengers raise the gross vehicle weight by 60% or so - and since the occupants can lurch forward on hard braking, and the front is rather rounded, it looks like it would roll end over end upon hard braking.
