Nigel, I would take issue with your "garage / (US=filling station)" etymology.

Nobody in the UK nowadays refers to a filling station as a "garage".

a "garage" is where you go to get your MOT done, get your brakes checked, etc.

a "filling station" is where you go to get your petrol.

No "garage" that I am familiar with operates as a filling station, although there may well be rural areas outwith my experience where both functions are combined.