Well so far, the Audi experience has been a mixed one. I picked up the car for £400 with a few faults which I knew about, and a few I didn't. The bodywork was in a pretty shocking state rustwise. Dentwise it was pretty straight but missing a few bits of trim. I have cleaned up the bodywork almost completely, but it still needs a few bits and pieces, but not too much and nothing major or expensive. It has a built in computer which my 406 was lacking, with various readouts including average MPG, average speed, time since last reset, miles left, instant MPG, etc, so my new game is seeing how high I can get the MPG. Since my first fill up I have done about 350 miles and the computer says I've still got 300 miles left. I'm also currently averaging around 47MPG which in a 4wd car is pretty impressive!
Sorry guys, but the ride in the Audi is so much better than the 406, but that could of been because I'd lowered my 406, although the A4 has the optional Sport suspension I think. There are also far less squeaks, rattles and knocks/bangs.
Talking of the mixed ownership, I switched the insurance to the A4 on Monday morning, got in the car on Wednesday morning with the little lad to take him to nursery and reversed along our little road turned into the farmyard entrance, I thought I heard something just as I was putting the clutch in but thought nothing of it, put the car in first and went to pull away and a horrible grating/grinding/rattling noise and no forward movement. Hmm, bugger I thought. Tried to pull away again and the same thing happened. Got the missus to take the little lad into nursery on her way to work and I set about finding out what the problem was. Jacked the car up and tried to spin the O/S rear driveshaft at the diff end, it span easily, so I looked at the other end of the driveshaft and the wheel wasn't moving at all. Hmm, double bugger I thought. Slid the outer CV boot down the shaft and 4 of the ball bearings fell out. Hmm, triple bugger I thought. Basically the race had snapped clean in 2 and with the car being 4wd drive, all the power was trying to be put to that wheel so no movement. Long story short, GSF gave me the wrong CV joint after an 80 mile round trip, so got the missus to pick up the correct new CV joint on her way home and it came with the ABS teeth on which the old one didn't have, put it all back together and I had drive again. As a bonus, the ABS light which was on previously was now out and the brake problem which the inbuilt computer kept flashing up has gone completely! The car in now more or less problem free, bar the bodywork and the fact that it needs 2 new rear springs as both are snapped at the bottom ring. I'll get some pics up eventually, but currently busy cleaning the inside as it looks like it's been owned by a builder or something similar as everything is thick in beige dust. The underside was also about 3" thick in mud when I got it and looked like someone had been having some fun offroading it! I spent an entire day blasting the mud with the hose pipe and there's still loads left under there.
Overall though, I'm very chuffed with my new purchase.
Feel free to drop in & let us know how you're getting on with it 
I seem to recall you had the parts to do it at one point. How much are you looking for the 406 mate?