Might not work.
There's an older guy that tried this by driving a truck off a sharp turn that had a decent drop off road.
He went in fast, flew off the road and slammed into trees.
He suffered minor wounds, his truck is totalled, and insurance doesn't cover that kinda thing. Wasn't a success.
Another guy drove his ATV off a fairly high drop. It took awhile to find him, but the ATV was totaled, and he broke his back. He was told he likely would not walk again. He is however after months able to walk with crutches. So he got lucky. He might not regain full strength, but he can walk.
These are two examples that happened within a year. Neither worked, and honestly I would've thought for sure they would.
One that did work involved a 20 year old driving drunk with friends. He was going too fast in a rural area and lost control. Went off road and hit a tree. He died, passengers lived. I hear he was impaled, but I can't know for sure. Its fairly recent so no details, just rumors.
I'd say its by no means a guarantee.
You'd probably have better luck tying a rope to a tree and driving away full tilt, thus yanking your head off.