Gas pedal is a North American term, not normally used in the UK. This is partly because the American word for petroleum motor fuel: "gasoline" (shortened to "gas"), is not used here, "petrol" being the usual term, although confusingly we do use phrases like "step on the gas". Another alternative word for the accelerator is "throttle" (from the fact that the valve controlling the fuel "throttles" - or constricts - the flow of fuel.)