If a roach was scaled to the size of a car, how fast would it be?

Let's say the roach is one inch long, one inch wide, and one inch high. The volume and therefore the mass equal one cubed.

If you double the size of Mr. Roach then you have 2 cubed which is 2 x 2 x 2 = 8.

A small car is maybe 100 x 60 x 60 = 36 x 10^4 which is 360,000 so if the basic roach weighed one gram then the car sized roach would weigh 3,600 kilograms, about 7920 pounds, just under 4 tons, and probably would be crushed without ever moving at all.