I kena both major problem for preve in the same week...OCH burst and gearbox failure.
OCH luckily burst while im driving to tapau breakfast, so can hear the sudden weird noise from engine bay...some were unlucky to have it happened while speeding on highways, which resulted in engine kaput. Got few workshop that provide OCH customization though.

And then, theres the gearbox failure, even after i drive it very2 carefully. But the signs/symptom of a failing CVT were not serious like others kena (jerking, gear free while driving, unusual whining), mine was, metal rubbing sound from inside the Gearbox whenever turning left.

Other than these 2 major problem, proton preve is a very good car, in term of safety, driving experience and performance.

when OCH burst, prepare at least 450, need to buy the OCH it self and engine oil...just pray it didnt happen when u driving fast and didnt realized it until your engine suddenly jammed

gearbox, there are 3 options,
1.overhaul (full rebuild, change damaged parts etc) costing around 3500-4500
2. modify (mix proton cvt with mini cooper cvt parts...heard many did this, but hard to find actual reviews about it, just some hear say saying its good and all) costing around 4500-6000
3. replace (they get new recond/new? unit from punch factory, and replaced 1 whole gearbox with warranty from factory it self) costing around 6500-8000

actually, my OCH didnt burst, just it got disconnected from loose clamp...mine was the semi steel och, which was difeerent than the full rubber originally came with the car