So the real car's engine volume equals 390 inches cubed. For this problem we don't have worry about units really so we will just say 390. When something is to scale like 1 : 18 it means that the model is 1 eighteenth the size of the real thing. So if you divide the volume by 18 it gives you the volume of the model. 390 divided by 18 is about 21.66, and 390 divided by 24 is 16.25, so the 1 : 18 model has the greater volume by about 5.41.
