I somehow got an oil stain on the plastic part of the floor mat (the bit where you rest your foot/heel) - most probably after filling up from a petrol station.

Can anyone recommend a product or a way to have it removed?

One of these carpet upholstery cleaners. It may be permanently stained.

Try swarfgell the hand cleaner type thing, it may help to put the oil back into an oily mix you can get off with paper towels.

I use swarfega & sand to clean my hands after working on the car.
In an emergency, I squirt my hands with WD40 - that really does shift the oil & grease - so may work on your plasticy bit.

Thanks for the advice guys! I bought one of those 3-in-1 grease removers, sprayed it, left it there to foam-out for a few minutes, then wiped it with a wet cloth. Repeated the process again, then left it to dry, and stain appears to have gone :woot:

Should come handy for other things like engines and lawn mowers..