Finding all Super Jumps in Burnout Paradise will unlock the Carbon x12 and the “Flying High” Achievement / Trophy. Most Super Jumps can be completed with any car and are accessable in free-roam right from the beginning. There are 5 districts the Burnout map is split into called Downtown Paradise, Palm Bay Heights, Harbor Town, Silver Lake and White Mountain. In each of these sections there are 10 Super Jumps to find and collect.
You can track your progress in the menu and see which super jumps in what district you already completed.
Here are all 50 Super Jumps by districts as collected in the video.
Palm Bay Heights
After completing all 50 Super Jumps you unlock the Carbon X12
CARBON X12 SHOWCASE (20:28)