I think L1ftmech is speaking of length of driving, while I think mrfixit, [the OP] was speaking in 'root means squared average miles per hour' driven in relation to number of engine revolutions.
For the equivalence to car's miles, I use a 'root means squared' average speed of 45 miles an hour, so the 30K x 45 gives an equal to having driven about 1 million, 350,000 miles.