Hey guys, I know JC from Top Gear did this a while ago in an A8 Tdi, from London to Edinburgh and back......around 800 miles.
Here's my scenario - A6 2.0 tdi with a full tank of fuel. Left Cumbernauld early doors (4am) and headed for Theale, nr Reading and just outside London. My boot was full of gear probably equivalent to carrying a teenage passenger I guess. Mostly motorway driving on cruise at around 80mph until I got to Leeds ( major hold up due to accident meant I was sitting in traffic for an hour and a half and it affected my fuel economy big time. As I was late I booted it for a while at around 100+ and got my colleague picked up at Derby, and on to Theale again at around 80mph.
On the way home dropped my colleague off at Derby and then onto Stoke via the A50 ( as there were still major problems on the M1 seemingly )
I filled up at Stoke with the dash showing 637 miles travelled and 90 still in the tank under the same driving conditions - a total of 727 miles
When I filled up and checked the computer told me I could espect 915 miles if I used the same driving style.
I fully believe that if I emptied the boot and drove around at 60mph on mostly motorways I could achieve in excess of around 800 miles every tank....lol
God it'd be so boring though
Anyways......just thought I'd share it with you
All the best
Jim