Everything! Initially repairs were handled by main dealers who were slow, unhelpful, sloppy and overcharged monstrously!
Main crank bent!
Piston rods bent!
Head gasket blown at 62000 miles.
Clutch assembly replaced twice (failing again before loss of car).
3 new radiators! This is caused in a large part by the stupid flimsy retaining catches which sit in little pools of water throughout their short life, so rust through and allow the unsecured radiator to flap around, the consequent flexing causing fatigue cracks. Replacement clips obtainable cheaply from dealers, but fiddly to fit.
Alarm never worked, eventually disconnected when it began to sound randomly while driving.
Always burned oil, smoked like a frightened squid on hard acceleration.
Always used water (where did it go? Never any visible leak).
Electric mirrors never worked.
Electric windows unreliable, worked intermittently.
Suspension components (bushes/shocks &c.) constantly replaced throughout life of car.
Brakes always performed poorly.
Brake discs replaced twice.
Brake discs warped and re-machined twice.
Rear drums useless.
Untraceable vibration from brakes throughout cars life.
Irregular wear in tyres (especially front) meant they required replacing sooner than general wear levels indicated.
External spare wheel a stupid idea: easily stolen and the lowering assembly rusted solid in mine which I only discovered in the pouring rain at the roadside!
Rust in bodywork (a rarity with most later Peugeots), chiefly in roof!
Warning lights and instrument panel lights unreliable - worked intermittantly.
Internal light switches on doors all packed-up.
Electronic headlight adjustment never worked.
Radio reception absolutely dire.
Needed several sets of glow plugs, probably due to oil being burned in engine - accessibility a nightmare as with most other DIY jobs in this car.
Paint peeled in sheets from bonnet.
Plastic trim faded badly.
Ludcrously flimsy plastic bonnet-prop retaining catch broken by every ham-fisted mechanic (including AA!) who ever looked at car.
Wipers ineffective, wore very quickly.
Feel and usability of gearbox in fast-changes rather poor.
Low seating position made glare from lights of oncoming vehicles at night a hazard.
Headroom poor, corresponding lowness of windscreen made car feel claustrophobic.
Seats bum-numbing after 3 hours!
Road and engine noise high.
I bought this car for weekly journeys of around 600 miles, it proved fast, economical and a reliable starter. The engine had good performance characteristics and could embarrass many a superficially more powerful petrol car.
It also proved to be a money pit, but in part because it had been owned by a "wannabe" boy-racer who'd thrashed it and failed to have it serviced regularly. Also, to be fair to the 306 I browsed reviews of other Peugeot models (inc. 307) plus equivalent Citroen's and it seems unreliable electrics, especially central locking and alarm are a PSA trademark, while complaints about build quality and unhelpful dealers are as common among reviews of Hondas, Volkswagens and BMWs as PSA cars. The whole car industry needs a massive kick up the ****!!!
Ride and handling of 306 have been greatly overrated by professional reviewers, mine was recently replaced with a 405 1.8 GLXi petrol which in every department except Peugeot's trademark unreliable electronics is a superior car, even though an older design.
Very much in the 306's favour is the fact it survived very well when hit from the side by a vehicle (Nissan Micra) travelling in excess of 30mph which never even braked. The car was written-off, but the 4 people inside the Peugeot walked from the scene with only a few bruises and a cracked finger-bone: the Nissan driver had to be cut-out by the fire brigade!
Amazing quantities of luggage could be carried with seats folded down and parcel shelf removed.