Superb - in my tips for speed driving thread I described a round trip of 600+ miles I did recently. I did the maths this weekend and worked out the trip down didn't take any more time than it did the last time I did it - also in a rush and not ED. The trip back took an extra 30 mins or so but some of that could be down to traffic and roadworks, but lets allow it to stand.
However usually I would have to fill up at around 400 miles so this was costing me a tank and a third. This time I didn't fill up at all. A tank costs me a roughly 53 GBP at today's prices so that 30 mins actually saved me around 17 quid (17.66), which works out at 34 quid an hour - not a bad rate.
I spent that extra 17 quid this weekend though to make up for being away for a couple of days from my son - we bought the Fifa world cup Wii game with it and played a few games. It was excellent dad/son time paid for by ED.
I know where I would rather spend my money
And of course this effect is amplified by the fact this was a business trip and so I get a mileage rate which pays me back the cost x 3
Mind you I won this afternoon's game vs Germany on that one unlike the real team. My son (Scottish) happily played as the Germans...