The A4 is marketed as a compact executive car, and as such is well equipped. Unfortunately time is not kind to these cars, and they age badly; my example was fitted with a new control module after water got under the carpet and fried the old one. This module controls the central locking etc, and is worth more than the car is worth. The car broke down after 3 miles with the fuel pump relay clicking merrily away to itself. For some reason when the battery was swapped for a charged one, it worked perfectly the rest of the time I had the car.
Also poor on the electric front is the light switch; mine would not select main beam, and eventually the dipped beam went away too. There are of course a vast array of switches available, so you physically have to have the old one with you when you order one, considering the switch was nearly the price of the car; I sold the car rather than replace it.
The BOSE radio was a total pain, it would come on a low volume, but if you tried to turn it up, it would either go silent or full volume; replacement is not a simple affair either.
The airbag light was always on, in fact every A4 I've ever seen has it illuminated, it seems to be a weak point. Also on the dash was the trip computer, which would sometimes cycle through its functions; other times it would randomly turn off, and other times it would only illuminate half the display. The self diagnostic functions are handy, but you really need to be able to turn the huge glowing symbol off for low fuel.
The climate control was most odd, emitting a series of groans from time to time. The aircon never worked, although the compressor clicked in with a thump and you manually had to turn it off. Also the temperature would fluctuate wildly even when set to 21 degrees.
Mechanically the car fared rather better. The 1.8 20v engine is extremely smooth, just not very powerful. It emits a lovely noise at high revs, and you will spend most of your time there as the car is geared lower than a Mondeo or Vectra. Even with the low gearing, it's no sprinter, acceleration is rather pedestrian. Rough idling was traced to a split vacuum hose.
Handling is brilliant, no other word for it, the A4 feels glued to the road, in a different league to the Mondeo, it feels like a hot hatch. Even with the rather mediocre 1.8 engine, it's possible to hustle down the back roads, yet the car is supple over bumpy city streets.
The car's main downfall was its woeful economy; although it was averaging 40 odd mpg on motorway journeys according to the computer, it was dreadful in town; it was not at all a rare occurrence to get the fuel consumption under 25mpg for a mix of town and country work. You could accept it in a bigger engined car, but not in a basic 1.8.
The car was rust free thanks to the galvanised shell, but the paint would mark at the slightest touch.
In short, the A4 was probably an excellent car when new, but it is distinctly in banger territory in its later years. The excess of electronics will kill it long before it fails mechanically.
Overall, I enjoyed my 3 months of ownership, but I was glad to see it drive away.