One of the challenges in the Saintsbook is "Windshield Cannon" - I have to launch myself through the windshields of cars until I've met a certain distance requirement.
I can't seem to figure out what causes me to fly through the windshield though. I found a sports car and fully upgraded it, then sent it full bore into the side of a guard rail. I didn't fly out. However, on my way to reset, I accidentally hit a nearby electrical pole at a much lower speed and I went flying.
How can I guarantee I'll go flying? Is there any easy way to max out this challenge?