I believe the 4.5 is a fake. I agree with BK, I got the 4.2's and the 200mah batt. But, I like the 3.8 in my cars better than the 4.2. It makes the cars faster than th 4.2. There was also a 4.8 on e-bay and it was a fake. Be careful buying the motors on e-bay. Usally Toyeast will get them before or just after you see them on e-bay.