Before drawing the real map I measured what the car can actually do. Ramps, gaps and bends are all designed around these numbers.
Top speed is 37 km/h. The car can climb any ramp up to 75°, but above 45° the wheels lose their grip on the ground and the steering and throttle stay stuck where they were. Stop on a slope and you roll back, and a ramp jump carries you 3.4 m at most. That gives the map two kinds of ramps: from 25° to 44° you stay in control, and from 45° up you fly off unless you hit them straight. The timer at the top starts with your first key press and keeps running even when you fall.