In store too, scanning £2.00 each
Probably worth pointing out you are pointing to the diesel variant and the deal is for the petrol variant. Also while you point is valid you could bulk buy lots to make your own cost effective version. These are one shot bottles you can keep in the boot and use at fill up every three months and dispose of the bottle in the bin at the petrol station. All with no fuss.
Here you go
Got any links for ebay?
Is this suitable for electric cars?