Sorry Toltec - I was a bit blunt before, and deleted the post.
Forgive me, but I've been worn down by a bunch of whiny Americans on another board, complaining about the cost of fuel but driving monster trucks with huge, gas guzzling V8 engines. When I suggest that they do have the option of driving something smaller/more frugal, they dig their heels in and start spouting off about "freedom of choice", and that if I "lived in a free country" I would understand. It drives me round the ******* twist.
Your situation is this. You're concerned only to be getting ~25mpg and you're looking for ways to improve on that. You've shunned the idea of a FWD diesel, and instead you're tootling around at 55-70mph, and have managed to improve consumption to a whopping <gasp> 28mpg!
What I'm saying is that the FWD diesel Skoda that you refuse to consider would be perfectly capable of those outings on the M20, cruising along at 70mph, and getting 50/60 mpg while doing it. My friend with the Skoda Fabia drives quite hard, but even she averages out at 68mpg.
But your choice is not limited to Skodas. I merely mentioned them because they are excellent value for money with VW quality. I know how you feel about FWD. I ordered AWD on my previous Audi, and it came as standard on my current Audi 3.0 TDi. Even the VW Golf TDi is now available with AWD, and the current 170bhp 2.0 diesel engine from the VAG group is a real stonker! The AWD variants usually take a bit of a hit on fuel economy, but it's well worth having. I average about 38mpg in my current car, with 43mpg possible if keeping the speed to moderate levels.
The choices are out there, toltec. If you refuse to take matters into your own hands, there's really no-one you can blame but yourself for those big fuel bills. If you would rather drive at 55 to get 28mpg than drive a diesel at 70 and get twice the mileage, well that's your choice. Good luck with whatever you decide to do.