Thanks to the high taxes we pay here a litre of Diesel has tumbled from a heady £1.29 to a (gasp) £1.22.
To get to US prices per gallon multiply that by 3.96 (litres to wimpy US Gallons - and yes the spelling is Litres and not Liters because Litres is French - deal with it) and then multiply by 1.60 (GBP to USD).
And yes we pay 40% tax on top of that, but we have an NHS