The reason cars do not use nikosil due to the high sulphur content in the fuel used. The suphur pits and corrodes the coating. It is only useful if you use very high octane petrol (100 and above).

The effect of nitro fuel is not known to me.
I belive it is not used due to cost, the plating is nickel based but it also uses less than 10% SILICON CARBIDE.