Sounds like a lot to me. For the first DARPA Grand Challenge, for example, no car finished the race. The farthest went 7 miles.

http://en.wikipedia.org/wiki/DARPA_Grand_Challenge_(2004)

The next year 5 vehicles completed.

http://en.wikipedia.org/wiki/DARPA_Grand_Challenge_(2005)

Also, consider all of the rocket failures in the 1960's and we still made it to the moon by the end of the decade.