Is the BMW M4 reliable?
The BMW M4 is a well made and robust sports coupe, but it does have a number of common faults, some of which serious, which you need to be aware of. The biggest concern will be the crank hub (read more below) which can cause major damage if it fails.
Reliablity goes hand in hand with maintenance and servicing so if you're after an M4 its worth spending a little extra on one with a decent service history. Maintaining an M4 shouldn't be an issue considering the plethora of BMW dealers and M car specialists.
Steer clear of modfified examples.
Engine: Crank hub failure can dramatically affect the timing of the engine, leading to a rough idle, a loss of power and – worst case – engine failure due to incorrect valve timing. Check if it’s been replaced and take the car on a long test drive to ensure it is running properly. Fitting a crank bolt capture plate is a sensible preventative measure.
The rocker cover, oil filter housing and sump gaskets can perish, so check for oil drips, and if there’s a distinctive tapping sound when you start the engine from cold, it could mean that the exhaust camshaft has become misaligned - an £800-£1000 repair job.
Turbos: Opinions on the lifespan of the turbos vary but they tend to show signs of wear after 50k miles.
Brakes: New discs and pads cost more than £1000 for a full set. Make sure there aren’t any vibrations under braking on your test drive because this could mean that the discs are warped.
