6in vs 4.5in of concrete for driveway
Ooooh, fiber mesh. Proprietary crap like that is how sellers pad their profit margins. It is like when car dealers sell you "undercoating".

The weight of the vehicle and thickness of the concrete does not matter. What matters is the subsurface. If the subsurface is solid 1" (inch) of concrete will support a cement truck. If it is not, it could break under its own weight no matter how thick it is.

This shows the cross section of a Roman road:



As you can see the pavement on top is relatively thin. What is important is the 10 feet of drainage and support under the pavement that makes the road last for thousands of years. The same principle applies to your driveway.