[burzum]

So, was the tree going 18 MPH or did gravity increase the car's speed?

The vertical component of their speed would have been about 50 mph.

Actually CNN noted that they hit the tree 15 ft above the ground changing these numbers to about 65 mph when they left the embankment, and about 80 mph on impact (45 mph vertical component). Either way they left the embankment at a very high speed which probably indicates they underestimated the braking distance required.

[relee]

Thanks for clearing that up. Math is not one of my special abilities.