Many car manufacturers will not allow freewheel diodes in parallel with relay coils, because the current decays too slowly, increasing the arcing. The preferred solution is to have a resistor in parallel with the coil, that takes around 10% of the coil current. When the supply to the coil is opened, the coil current flows through the resistor, resulting in around 10 times the supply voltage on the coil, and the coil current decays quickly. The surge voltage is well defined, so whatever supplies the relay coil, normally a semiconductor, can be specified for that.
If you have a DC relay supplied from AC with a rectifier, you will get the current decaying slowly. I recently repaired a refrigerator where that had been done, and the relay had failed as the NO contact was welded closed. That is the contact that would have suffered the worst due to the coil current decaying slowly.