Conventional vehicles like the 4x4 ambulance shown below are not 'mine-protected' by design, but they still offer some protection against small devices.
For example, a PMN (240g TNT) detonation beneath the wheel of any 4x4 will not usually result in injury to an occupant – although the vehicle may go out of control and crash causing injury. Just as the thin bodywork of a conventional car can protect against a small blast, so it may stop or deflect fragmentation from small devices, or from larger devices a long way away. I do not know of any cases where an AP blast mine detonating under a wheel caused a fire, but they may have occurred. So, in general, AP blast mines are not a threat to conventional vehicles - although if they cause a crash, they can be an indirect cause of injury. The real threat to an unprotected vehicle is an AT mine, or a large improvised device. The unprotected vehicle below hit an AT blast mine. It was thrown into the air, severely damaged - and its long-range diesel tanks ruptured and burned. This was a demining ambulance. The occupants were very severely injured.
The materials involved in any blast event are relevant. The weakest point of any standard vehicle is the glass. When struck by fragments it may shatter or simply be penetrated. When struck by sufficient blast it will shatter and each bit of glass will become a sharp edged fragment moving at high speed. Drivers of conventional vehicles often want to buy something that will upgrade their machine enough to make them safe to drive in areas with a landmine threat.
Personal security companies offer a wide range of 'bullet-resistant' conversions for conventional vehicles. Some look very dubious, but others may work against conventional handguns and ordinary ammunition or against a fragmentation mine (as long as the fragment strikes are not concentrated on the glass areas).