I know this is not totally relevant - but it does underline the tax situation that you guys are in, in the UK - and it also shows about rip-off mark-ups.
Cheapest Florida fuel: Pahokee 31 pence per litre ($1.82 per US gallon assuming £1 = $1.50 and 3.85 litres to the Imp Gall)
Dearest Florida fuel: Miami International 71 pence per litre (same mathematics)
How can one place charge $1.82 and a close neighbour charge $4.09??