ORIGINAL: eddieC
Call a physics prof at a local university. Give them vehicle weight, length of building to clear, est top speed. I'd guess an angle 45-50 degrees.
TLJAR.
LOL...it's only high school physics, so that makes it easier when looking for advice, but in all things, there's theory and then there's reality where unforeseen factors play a major part.
The angle also depends on how close you are to the bldg you want to jump. If I wanted to do this, I'd experiment in an open area with a 45 degree jump first, and tailor it from there.