Trucks carrying bowling balls

Tom and Jack each own identical trucks, on which they each carry an equal number of bowling balls with equal weights. Tom keeps the bowling balls loose so they move around on the truck, while Jack has them tightly secured.

If they travel the same route with lots of bumps, pits, and stops, then whose truck will consume less fuel?

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Details and Assumptions:

• Both the drivers are equally skilled.
• Air drag and other factors that may affect the fuel efficiency of the trucks are also exactly the same for both the trucks.