Development Build #-1.07.113027
The Zamak vehicle's seem to be lacking suspension. The axles are slanted sitting on a level surface with almost all of the types of Zamak vehicles.
They also seem to have the rear wheels are slightly elevated instead of the correct height like all the others. When turning its basically looks like you have zero suspension on the trucks at all.
Place any Zamak vehicle(Zamak Fuel does it 100% of the time) from the "Empty" category and look at the rear wheels as well as test drive it.
You will also notice that the Zamak Fuel truck also sits very uneven on the ground and the tires are clipping through the ground.
Zamak Fuel
Zamak Ammo
Zamak Repair
Zamak Medical
Vehicles placed on the Altis map from the "Empty" category.
I placed them at the giant airport in Altis.