Just to prove to you that this isn't crazy, let's answer the question "How long will it take a car accelerating at ½G to do the quarter mile?" We invert the equation above (recall your high school algebra), to get

and we plug in the numbers: the quarter mile equals 1320 feet, a = ½G, and we get

which is about 13 seconds. Not too unreasonable! A real car will not be able to keep up full ½G acceleration for a quarter mile due to air resistance and reduced torque in the higher gears. This explains why real (stock) sports cars do the quarter mile in 14 or 15 seconds.

The more interesting result is the fact that it takes a full second to go the first 8 feet. So, we can see that the launch is critical in an autocross. With excessive wheel spin, which robs you of acceleration, you can lose a whole second right at the start. Just visualize your competition pulling 8 feet ahead instantly, and that margin grows because they are 'hooked up' better.

For doing these mental calculations, it is helpful to memorize a few squares. 8 squared is 64, 10 squared is 100, 11 squared is 121, 12 squared is 144, 13 squared is 169, and so on. You can then estimate square roots in your head with acceptable precision.