Seat height adjustment handles on both front seats have broken off twice. Replaced under warranty.
Driver's seat developed a nasty creaking noise in the frame at around 25,000km. Dealer replaced seat frame under warranty.
Indicator stalk broke inside the steering column, which made the high-beam headlights switch on at night whenever the indicators were used. Fixed under warranty. 35,000km.
Numerous squeaks, rattles, and creaking cheap plastics used in the cabin. Some problems fixed, others impossible to fix.
At 66,000km the timing chain snapped in the engine, causing bent valves, damaged pistons, and other damage. Dealer said this is the first time they have seen a snapped timing chain on an A-Class (read below).
Hot water hose from the radiator developed a leak.
The front seat height adjustment handles are very fragile on all German A-Classes built before May 2001. Just two small plastic tabs turn a metal spigot on the seat. I used the handles maybe 5 times before they snapped off. No undue pressure is required as they are quite fragile. After replacing four on my car (one just minutes after I drove the car off the dealer's parking lot) they used silicone glue to help reinforce the handles on the seat.
As other reviews point out, the interior quality of pre May 2001 A-Classes is marginal. For some reason Mercedes-Benz chose to use a hard plastic that creaks and groans, especially the silly trim around the passenger seats. I ignored it at first, but eventually plastic quality with all the creaks and clicking noises when driving really annoyed me.
Another common problem on the older A-Classes was the driver's seat frame, which would develop a loud creaking noise whenever weight was shifted on the seat (changing gears was enough). The dealer offered to replace the frame with a redesigned model without hassles. Initially they just tried lubricating the seat, but that did not help.
The indicator stalk issue was interesting, as it was impossible to avoid turning on the high-beam headlights at night when turning with the indicator on. The dealer replaced the indicator stalk the next day, but I must have annoyed a lot of drivers in the city that night.
The final nail in the Mercedes-Benz quality coffin was the timing chain. In early October 2004 I complained to the dealer (car is now out of warranty) that there is a strange two tone noise coming from the engine bay. Difficult to explain, but it was definately not normal. It got faster with increased revs and the airbox in the engine was shaking quite violently. A belt pretensioner assembly was changed in the vehicle for AU$500 plus labour, but this did not fix the problem. The dealer rang telling me of another noise coming from the engine bay, and asked permission to look under the rocker cover. From their tone of voice they sounded like they thought I was a very fussy car owner who wanted every noise eliminated from a car.
So they had a look, and found a seized link in the timing chain. They had never seen anything like it, and ordered a new chain. This was going to be an expensive repair as the timing chain is not designed to be changed in the A-Class: Its sealed for the life of the engine. I drove out of the dealership and less than 100km later the timing chain snapped in the engine, causing valve, piston, and other damage. The A-Class has a non free spinning engine, meaning damage is caused if the chain snaps. Remember this happened at only 66,000km!
All the valves had to be replaced along with various gaskets, piston parts, and minor damage to the engine block. Fortunately DaimlerChrysler agreed to pay for all the repairs on my vehicle even though it was out of warranty. They found a snapped timing chain in an A-Class to be unacceptable. Without their help the repair bill would have run into many thousands of dollars, as there is a LOT of labour involved in removing the A-Class engine (basically everything from the front is removed).
The A-Class has a funky design, and I really liked my A160 petrol funshift Avantgarde despite all the problems. However, the timing chain failure was the last straw. I simply could not keep the vehicle.
The car is roomy and has quite good performance. Beware of dark coloured paint, as it is very easy to scratch. The Funshift transmission is a joy to use and gives all the economy of a manual.
Safety is excellent in the car, certainly better than a lot of other much larger cars.
Mercedes-Benz have built the A-Class down to a strict budget. Repairs are numerous, quality is so-so, and parts are very expensive. Please look past the gleaming Mercedes badge when buying your next vehicle. Friends have commented 'how could Mercedes build a bad car?' with puzzled expressions. I tell them any company can build a poor quality car despite the prestige of their badge.