In a few weeks I need to do Newcastle to Kent. I'm trying to weigh up between taking the frugal Up! and the M3. I know the BMW will be better for blasting down the motorway but will only return around 20-25MPG depending on what speed you cruise at. Realistically what will and Up! give you on a motorway run (75PS BMT). Also what are they like at motorway speed? The only reason I ask is because I'm still waiting on mine arriving!