In today's world, a flat interior floor is a rare and desirable thing. It makes it easier to move around in the cabin and gives the middle passenger(s) more legroom. Usually it's a sign that the vehicle has front-wheel-drive or is high enough that the drivetrain could be packaged below the floor without the need of a tall transmission and driveline hump. The 1962 Buick full-size line trumpeted this feature, apparently achieved by moving the engine further forward. The other feature advertised that year was the so-called 'Advance Thrust' of the Wildcat V8 engine. Advance Thrust sounds like a condom brand or something, but it was supposed to convey the immense power of the engine that could flatten hills - or at least climb them quickly.
This ad appeared in the October 27, 1961 issue of Life magazine.
