Water Pump plastic impeller through it blades off at around 50,000km. Replaced with a metal aftermarket pump at $90 and never had a problem again.
One ignition coil failed while out driving one day at around 90,000km. $80 for a new one and fitted in a couple of minutes.
Driver window failed at 110,000km. Took it to a dealer and was fixed cheaply. Common failure of plastic clip, but replaced with updated metal wrapped clips. Total around $220.
Plastic water distribution block mounted on the head of the motor developed a pinhole leak at 145,000km. $23 for a new one.
Generally a reliable car, and has been cheap to maintain and to run... for a euro car. Genuine parts have been cheaper than any car I have ever owned.
It has also been very good on fuel, averaging in the 8L/100km range for combined city and freeway driving. Best has been 880km from 50L (5.6L/100km) on a drive from Sydney to Melbourne and not taking it easy also.
Performance-wise I would not really call it a GTI. Acceleration is not that great compared to its Japanese competition so don't plan on taking on anything but NA motored cars unless you do a few mods. It has a strong midgrange surge of power, but dies higher in the rpm. This shows why it only puts out 110kw in standard form. Mostly this midrange strong powerband comes from the tiny turbocharger VW has chosen to use. It responds well in the lower rev ranges from 1800 to 4500 rpm but elsewhere it is lacking. The motor really needs a higher compression ratio and a larger turbo to improve the lower and higher rpm ranges, with a slightly lower final drive to help bring it up on power sooner. The ECU is the first place to look for those looking to improve things on a budget. I used a Haltech Interceptor which ran perfectly and gave a significant increase in usable power between 2000 and 6000rpm, dropping it from 8s 0-100km/h to running in the high 6's. I have done 100,000km on the higher power setup with no engine problems at all. Still runs like the day I bought it.
It handles OK, but is let down by overly soft suspension and bushes, together with a short travel which crashes on heavy pothole hits. If driven sedately it is very comfortable, but driving in this way is not what a GTI is built for. Start to push it hard and significant body roll kicks in which is accompanied by heavy understeer and then running wide in the corners. The best and cheapest cure for this is an add-on rear swaybar kit. A 22mm solid bar did wonders for my car, with much tighter body control and no trade-off at all with comfort and it also does not induce any lift-off oversteer. The car should have came standard with this level of rear roll stiffness. At a later date I replaced the shocks with Koni Sport adjustables which IMHO are more comfortable in ride than the OEM suspension. At the same time I replaced with springs with 15mm lower Eibachs, and swapped the 22mm add-on swaybar for a 26mm adjustable. Overall the car handles supremely better, but drives just as comfortably as standard did and limited the bottoming out of the suspension under hard hits. It still does it but nowhere near as teeth-rattling.
The brakes standard have been more than up to the task, and when the rotors wore to their limits around 100,000km I replaced them with aftermarket slotted rotors but went with OEM pads which work well. Fade resistant and work from cold, but do throw a lot of dust.
Interior-wise the GTI is well appointed. Factory Recaro seats with height and lumbar adjustment make it easier to suite everyone. However, to this day I find it difficult to get 100% comfortable in them. It is something to do with the curving of the backrest which no matter how I adjust things I always feel slightly hunched over. It is not that bad, but it is there. The fit, finish, and design was, and still is, years ahead of the Japanese cars. It feels like a car worth double, and with 150,000km on the clock the seats are still in almost new condition and the general feel of the car is like new. The sunroof rattles, and has done so since I bought the car, with it not getting any better or worse. For the most part the interior is a pleasant place to spend time.
Exterior-wise it is a well built machine with an excellent paint quality and panel fit. The paint on my vehicle is in perfect condition with no visible orange-peel and an extremely heavy clearcote which makes it easy to polish and keep in good condition. The sheet metal is tough and very dent resistant. I recently was stuck in a horrible hail storm which demolished houses around the area, and when I arrived home there was not a dent to be found. One tough little car!
For the most part the Golf GTI 1.8 Turbo has been an excellent car to own. It is generally reliable and has not had any major breakages, just a few little things once every couple of years which I can't complain about.