Thanks; won't be doing a lot of driving on the Island and will arrive there with the tank probably still two thirds full so more likely to be filling up after getting back to Lymington - will have more time to spare on the way back anyway, so I'll look at Pennington.

1996 Suzuki Swift automatic, 993cc.

Consistently does 50+ mpg combined cycle with premium unleaded compared to 35 - 40 mpg combined cycle on the regular stuff.

Allowing for the price difference at the pump it works out at about ½p a mile cheaper, but more important than that it keeps the engine really clean AND gives me a lot more miles between filling up.