I had a TDi 75 but now own a 1.4 Sport. My motivation for acquiring it was the colour (Pearlescent Merlot) and the Twist leather interior. Thanks Ami! Like some people have observed, I found it a bit 'weak' coming from the diesel.
I put this down to the following (all of which I have dealt with):
1. I had forgotten how to drive a petrol car. I had become very lazy on biting point. The diesel is almost impossible to stall! I also changed up too early and kept having it in the worst part of the torque curve.
2. I started putting VPower 99 in it and it progressively got faster. I don't know whether this was due to 96000 miles running on supermarket fuel 'gumming' it up and the VPower cleaned it or it just likes the high octane fuel. I haven't stopped using the VPower so will probably never know!
3. I swapped the 17" RS4 alloys for some nice 15" Ronal A1 alloys, kindly supplied at a good price from A2Steve. These wheels are much lighter. I put a new set of low rolling resistance Bridgestone Turanzas all round. Both these mods gave another boost in performance.
As Bargepower says above, I do not have any trouble on the motorway or more to the point, the A1 (more hills) which is where I spend most of my open road time travelling between Sussex and Yorkshire. The last trip delivered 48mpg and on the odd occasions I could do 70, I did.
I have the the excellent Timmus colour DIS fitted and with no open road stuff since last September it shows that I have done 1190 miles at average 20mph and 35mpg. That's not diesel territory but reasonable in my opinion. I'm not sure if it is a lot worse during a cold winter, as I never seemed to warm the diesel up on trips between November and February! Never had DIS on the diesel though.
I'm sure others will disagree but although I loved my diesel, I find the petrol better to drive. If I give some revs it on the back B roads, it gives me tons of smiles! If you use 2nd, 3rd and 4th well you can really surprise other drivers, although they sometimes get a bit shirty when they see the '1.4' on the back...