Answer:
24 !
Explanation:
I can be wrong... but if I remember correctly, by multiplying all three numbers together and getting 24 possible variations, you're taking a shortcut of just matching, for example... one color with three diff interiors and 2 diff engines, one at a time... Whether you do it long-hand like that or just multiply the numbers altogether, you still get the same number of variations. It's just a quicker method to solve this
4*3*2=24
hope i helped :) !