The driving conditions were perfect for such a test, very long FLAT roads 50 - 60MPH and VERY light throttle. I was trying so hard to get the MPG as high as possible it was actually wore me out.
Remember that Top Gear episode where Clarkson took an Audi A6 V8 TDi to Scotland and back from London, well I was driving like that (apart from there being 2 adults, 2 Tea Pot Lids, heater on, heated seats on, and all lights on).
Anyway, the result of my efforts, and believe me I tried very hard, was 53.3MPG.
Pretty good, but not as much as I thought. Bearing in mind I never went over 2000 RPM once, and I was going for a record.
It stabilised at 53.3 after 1.5 hours and if I reached a slight incline and squeezed the throttle it went down to 52.3 average.
The car was actually doing some weird things too, it sounded really clattery and if you suddenly accelerated it took a while for it to catch up and belched out some smoke, like the ECU was running on a cruise setting for so long it had altered all its usual settings??
Whats your best? and should I stop acting like your stereotypical ''I drive a Diesel and I'm going to boast about my MPG even though my car still costs a small fortune to run compared to your nice quiet punchy, BHP'y, Petrol'' owner
