Fuel economy on a 25 year old T25

So while the T25 still offers a cheap way into the life of camper vans, the pay off (or not) is the MPG that it offers. Looking at it basic 'brick' profile, it comes as no surprise that a 2.0 air-cooled petrol engine may only offer only 20 to the gallon. So the question is, how do you improve it and what's the best options?



Petrol engines.
If kept in good condition should offer 25 miles to the gallon, and at current prices that means a 200 mile round trip would cost something like £40 which isn't too bad, but surely the diesel would offer better MPG.
Diesel engines.
The answer here is obviously yes. But while the 1.6 offers much improved MPG with something like 30 to 35 MPG, making the same 200 mile journey something like £30, it is said that the standard engine is somewhat gutless for the T25s needs. People think that swapping out the standard engine out for the later 1.9TD can offer 35 to 40 MPG with speeds of 80mph easily capable.
While I'm not looking for major engineering feats and insurance complications, I will be looking for a standard diesel and look to have the fuel pump upgraded to help with economy. There's also the added option of bio fuels should you take the diesel route too!

Sent from my BlackBerry® wireless device