A free mod for 7 Days To Die, by Lam.

Lam’s Increased vehicle storage is a mod that allows you to increase the storage on all vehicles, including bicycles, minibikes, motorcycles, cars, and trucks. This is accomplished by simply increasing the values of certain variables in the game. The amount of increased storage varies by vehicle but is generally more than what is currently available. 

The installation of the mod is accomplished by simply opening the.mcworld file that is located in the installation directory. There is one variable that is increased, and all other variables are left unchanged.