"Note- I am taking no credit for this glitch, I do not know who found it.
Steps:

1. Get the armored Kuruma and a tank
2. Drive the tank over the Kuruma (You are basically trying to break off the tires)
3. Break off all tires except for one of the back ones (seems to work if you break off all the tires as well)
4. Have a friend get in the vehicle as he/she is getting in have them hold the aim weapon button and the duck button, If done right the passenger door will remain open.
5. Have the driver of the car start doing a burn out and then at the same time push the analog stick left or right
6. If all goes well the car will spin and launch, The physics get really weird with this when you do fly....

Notes - Door must be open for this to work if it closes or breaks off you wont launch you will just spin in circles on the ground. It can take awhile to break the tires off, Keep trying. Don't hit the car too hard with tank or it can blow it up!"