I don't recall the General going vertically upwards. Bo and Luke's motor seemed to lack an engine when "flying" over rivers etc because if it had one, it would have gone vertical quite rapidly (down).
They actually did, but they filled the trunks with concrete to level them out in flight.
Here's a jump the Duke boys would've been proud of, in what appears to be an unmodified Buick LeSabre.
If you're counting brief hops, the 1917 Curtiss Autoplane, "It was able to hop, but not fly."
The show averaged slightly over one car destroyed per episode - over 300 during the production run.
I’m curious about the condition they’re usually in when they land.
I remember reading that there were actually about 25 General Lees. Pretty much every jump totaled one, and they'd swap in another, and haul off the first one to get fixed (or junked).