Oil pressure gauge is a good thing to have, saved me an engine once (shop forgot to put the drain plug back in, car started with 0 pressure)

Volt meter is fairly useless..

Never seen an MPG gauge except in those U-hauls, and god only knows how those things work (though I do think it'd be neat to run)

IMO, run an Aeroforce Interceptor, and a Wideband O2