With my 996 Carrera 2 withECU, Exhaust and Intake mods I can safely do 300+ miles in the UK on a tank with reasonable driving (cruising at 75-90 mph) getting according to the computer about 27 mpg.
I have a regular 340 mile drive, so I usually stop for fuel30 milesbefore I get to my father's at a low cost (but good) fuel stop. I could probably do the whole distance, but would then have to pay premium prices for the super unleaded.
Anyway its OK. Better than the F150 Harley Truck that will do the 340 but nearer 80+ litres.
Regards Big Bob

 

I get about 300 miles out of a tank, unfortunatley I'm not allowed to cruise at 90...except when passing on occassion.

Big Bob--do you guys have high speed highways like the German autobahn? I remember when I was in Germany, you would calculate a 500 mile trip in about 5 hours, averaging 100 miles an hour.

 

Sadly not, we are officially limited to a maximum of 70mph on Highways. However I do much of my long distance driving at night or early morning, so with less traffic on the road it is easier to detect "smokies". And providing you are not caught doing over a 100mph, then its not too painful. Hence I try to cruise between 75-90.
Regards Big Bob

 

Yes, occassionaly I miss the German autobahn. Although last time I was visiting, I'm starting to see more and more 130km speed limits.