Faults:
Door light switches were corroded.
The clutch cover plate 'hardened', which had to be replaced.
Poor rear wash/wipe (depends on which revision tailgate the car has).
Poor front wash, but is easily fixable.
General Comments:
An absolute belter of a car in terms of comfort and performance. Feels best on your favorite twisty B road.
Interior comfort isn't brilliant - the seat backs seem to be an odd shape and I had difficulty getting comfortable. If you're keeping it for some time, invest in some Recaros!
Interior generally looks slightly dated and can wear easily, but as long as you take care of it, this shouldn't be a problem.
Do not be tempted to lower the suspension too much, and don't fit big wheels. This completely ruins the cars ride and handling. 17's are fine on a glass smooth track, but comfort and predictability suffers massively on the road. Peugeot spent a huge amount of money to get it right - why pay £500 to destroy it again?!!
Maintenance and running costs are disappointingly high. Do try to buy high quality replacement parts when needed. Fuel costs day to day are high if it is driven quickly - if you don't, what's the point in buying it?
Cam-belt tensioners are very critical on these engines. A large batch of poor tensioners were fitted too many a 306 and some have been known to fail at 25K miles. If in doubt, always replace the cambelt, water pump, roller and tensioner. At a decent garage this is a £300 job.
Clutch cable tensioners can become stiff, but are a fairly simple and cheap job on a Rallye (GTi6 has AC to contend with!). This causes a stiff pedal - if it's still the same after changing the cable then it's a new clutch. The heat produced by the engine causes the cover plate to harden, causing the stiff clutch. Clutch change is another £300 job if done by a garage (including parts).