After watching the recent economy challenge where the jag won the race to do 750 miles on one tank, it got me wondering if it were at all possible in a Merc! The most i remember reaching was 600miles on a round trip to scotland in my e320cdi. As my car has just been written off and i have been borrowing cars from friends and family i set about finding the car for the job. Right under my nose, my dad had just picked up a dirt cheap 2000 E220cdi classic with a 6 speed manual - perfect for the job, having the same size diesel tank as the e320cdi. The car in question is a pretty standard model with 205/65/15 tyres on steel wheels, has 125,000 on the clock and runs purrrfectly. Oh and it's black, which definately helps the testing! On my first day of testing i reached a brilliant 61mpg. Second day 62.9 mpg third day 66.9 mpg I stupidly started "practising" my economy driving skills without filling the tank, so i'll have to fill up tomorrow and start the test again. Although not quite as fair as their test where they could pretty much just drive all day long, i'm just driving over 30miles to work and then back again every day, but we'll see if it can be acheived and if the On Board Computer is accurate at all. The On Board computer reports 14.2 gallons once filled to the brim, while mercedes quote it as having a 17.6 gallon tank. If the on board computer is correct and it really is returning 66.9mpg that means a tank could theoretically return 1177.44miles. That of course, is an outrageous figure, that i'll never achieve, but it will be interesting to see how close i get. My driving tactics are as follows. Cruise control on at 56mph, so as to never slow down slower than a truck, speed upto 70 on the long down hills (coasting where possible) to make the engine work less on the up hills as i nurse it back down to the 56mph on the up hills. OK, this is all a little extreme, but i like a little experiment from time to time. And seeing as a lot of traffic seems to travel at these speeds anyway these days, i'll take a few weeks off from the outside lane for the benefit of this test. Any comments/input welcome.