Mouse Trap Car Science Project

This is my science project for testing putting different objects on my mousetrap car. I tested the different distances and speeds. These Items are, a hardrive, a book, and a drink.
I think that the harddrive and the phone will go approximately the same distance since the weight is approximately the same. The book will probably go the least distance since its the heaviest.
I tested it on the driveway of our house. First was the hard drive. IT went approximately 75% of the way there.
I tested the drink next. It was filled 20% of the way up. It wet 3 inches more than the harddrive did.
The book was last. Even though it was the heaviest, it went all the way to the end of the driveway and onto the road.
In conclusion, I was wrong on how I thought that the Book would go the least distance. I believe that it went the furthest because I think the ratio of the arm length to the distance it has to pull, is too powerful for the axle. With the book, there's more weight and downforce to keep the axle from spinning out.