For me it feels like the first few and final jump are the trickiest. After I made it to the first checkpoint I managed to get the highscore by 23k on the same attempt. Hard to say whether it was a fluke or that most of the rest was fairly sight-read friendly (which is a good quality for a level).
To get past, you have to jump early! So when you jump, basically on the downhill slope part, jump a bit early, and you'll fly toward it. Jump to get the head of the car over the sticking up part, and pull yourself over! Thats the best I can describe it! Make sure you go back as far as you can for optimum speed!