It would depend upon the type of RC Rock Crawler you purchased. If your current RC Rock Crawler doesn't go as fast as you would like it, you can consider purchasing parts that would increase it's speed. Visit http://www.rcplanet.com/Rock_Crawler_Parts_RC_Radio_Control_s/1587.htm to find out more.
It seems as if the RC Rock Crawler is supposed to go very slow. Not all products mentioned the speed however on one product the speed is 3.2mph. So since the crawler is known more for the ability to maneuver over rocks then for its speed.
With the stock electronics its not going to hit more than 15, but you can upgrade it with the losi xcelorin brushless system and lipos, and it will go about 25...
10 mils
It is quite fast for the average RC car except for now there are RC cars are available to go 100 MPH
100 mph
65MPH
It can go from 3mph to 15 mph.
about 50
366mph (516kph)
I have been looking at rc boats and i saw one that go's up to 20 miles an hour but i didnt know if that was a fast electric boat.
About 45mph maybe 50mph for .21 engine
About 20mph out of the box