Most vehicles obtained this way won't be sellable or will only sell for GTA$50,000, but some Arena War vehicles will sell for up to GTA$1,000,000 if you spawned them fully tuned. We recommend the Future Shock Deathbike (deathbike2) for this purpose.
However, you should keep within the safe limits when selling vehicles:
Not more than 2 sales per 2 real-world hours.
Not more than 7 sales per 30 real-world hours.
Filling The Garage
There are a few ways to fill a garage:
Buying free vehicles on legendarymotorsport.net
Stealing cheap vehicles from NPCs
Spawning cheap vehicles, like the Ruffian (ruffian)