I've got a 225. The main things I can think to look out for are:
Cambelt + aux belt history, preferably done by Renault or by someone who knows what they're doing.
Electric window regulators are known to fail so check the windows work. I've had my drivers side window done. Renault pay a massive chunk of the cost with it being such a common problem. I think it'll cost you around £120 a window to sort via Renault.
Exhaust hangers are known to fail which makes the back box/exhaust tips wobble all over the place. Make sure this is nice and secure.
The water drain holes under the wiper mechanism are known to become blocked with leaves, twigs etc which ends up leading soaking the interior carpets. Check for a damp floor as it's nightmare to dry out from what I've read (basically a full interior strip). The passenger side door pocket also can fill with water too (unrelated to the main water drain holes). I currently have this problem!
I can't think of much else... I'm sure I've missed some bits though. Might be worth checking out Meganesport.net or RSMegane.com for a buyers guide
All very valid points, worth looking for when buying a Megane.
Also check the service history, for the spark plugs, and most importantly the Coil packs, when they where last changed?
Megane's are know to kill them quickly (seem's circumstantial) , leaving the car on three cylinders. It would get you home, but it's never fun.
In the six, years I have had mine. I have serviced the engine every 12 months (Oil, Oil Filter, Spark Plugs), an within days of buying it, I bought 4 new coils to be safe.
Since that time, I have had 2 coils die, and it has never let me down mechanically (waiting for toe truck.)
As for the coils, there only £25-30 each. And five minutes to take one out, restart the car, and check them, until you find the faulty one.
Has been my first, and only car to date, and I absolutely love mine.
Comfy-ish (Depends on speed) + well kitted for a 2004 car + economical as a daily; But immensely quick for 200+BHP Front wheel drive car, and when on twisty, A roads, boy they are fun, an very responsive.
EDIT: Also if your buying one. Check the tires, most Megane owners recommend Continental Tires. I have Continental Contact Sport 5. I only ever had hairy moments on the snow. In the dry, or wet the car is perfectly planted.
