dude modern cars are fine and if they dont make it 4 years then they're just a shit manufacture lol.
Thats if they're looked after ok...
failures on 3yr old cars:-
tyres worn down to cords (bad alignment usually down to pothole damage to suspension)
brake pad/discs worn down/defective
brake fluid defective (basically brakes fail brake test section of MOT)
broken springs, or defective ball joints (Pothole damage to suspension)
seat belts frayed
Headlights & other signalling defective...(blown bulbs)
Many cars at 3yrs old the owners haven't bothered getting ANY of the basic servicing done....oil change??...brake fluid change??....check tyre pressures??