No mechanical failures at all. The engine runs like new. The transmission shifts perfectly.
Electrical problems are prevalent throughout the car.
Wiring for engine harness degrades over time. If you buy a 240 built before 1988, be sure the harness has already been replaced.
The tailgate wiring becomes severed over time and renders all tailgate electronics (wiper, defrost, electric lock, license plate light) inoperable. Easy replacement if you know how to wire up simple electronics.
The ventilation blower motor failed long before I purchased the car and was not replaced. Replacing it myself required over 10 hours of labor on my part. It is strongly advised that you buy a car which has had this motor replaced.
The engine computer in 1983-1984 models is notorious for going bad and causing no start conditions. Buy a car in which the computer has been replaced already, or avoid this year altogether. A used working computer can be purchased at Ebay for $50. A new one from Volvo costs $900.
The driver' seat is badly worn, and bottom support springs as well as lumbar support were broken when purchased. Finding a seat in a junkyard would not be difficult and it takes literally less than 10 minutes to replace.
Aside from that, a very reliable car. I would not hesitate to buy another Volvo based on reliability alone.
The main reason I would not buy another non-turbo 240 (or any non-turbo Volvo for that matter) is performance.
The engine in this car, though remarkably reliable, is horribly overburdened with the task of hauling around a 3,100lb car. Acceleration borders on dangerously slow. This was a serious oversight on Volvo's part. Getting up to speed on any road near my home requires over ten seconds of full throttle acceleration. This is an accident waiting to happen on a busy day. If you are at all interested in even a respectable level of performance, do not buy this car.
Handling is biased heavily toward understeer. It is very difficult if not impossible to cause this car to spin under even flood conditions. This car's handling abilities are compromised by its ride-biased suspension tuning.
The ride quality of the car is excellent. It floats fairly smoothly over most roads, and doesn't jar much on bumps.
The brakes work astonishingly well. The four wheel discs do their job superbly. If it weren't for every other driving dynamic being so poor, hammering the brakes would make you think you're driving a race car.
Noise level inside the car is definitely not befitting of a company desiring a luxury car image. Engine noise can get to you at times. Dynomatting or adding insulation near the firewall takes care of most of this.
Comfort is very good in all seats. They are well designed and supportive, though offering no lateral support during corners whatsoever. The rear seat legroom is excellent. Passenger seating all around is spacious.
For the driver, a few missing amenities add up to aggravation over time. There are no cup holders in the car. The small storage areas in the center stack console are effectively useless. Anything left in the change tray will be on the floor within a day as it holds onto nothing. Lack of cruise control is a big minus. For a manual transmission-equipped car, a tachometer is sorely missed. Though the car has no effective power-band to exploit, a tach is still necessary in my book.
Fuel economy is fair. For a car this size it isn't bad, but I've seen cars with twice the horsepower that get better gas mileage. I get on average 20-23mpg in a 50/50 city/highway mix.
Overall, it's a good, reliable car with lots of cargo area, and it's slow as hell.