Depending upon the cause of the fire it could be covered if you have comprehensive coverage on your vehicle.

Comprehensive coverage is an optional physical damage coverage that normally covers your vehicle, and sometimes other vehicles you may be driving for losses resulting from incidents other than collision. For example, comprehensive insurance covers damage to your car if it is stolen; or damaged by flood, fire, or animals. Comprehensive coverage should pay to fix your vehicle less the deductible you choose if the insurance adjuster determines the engine fire is a covered loss under your policy terms.