I agree with eye30, for that sort of mileage petrol would be better, and the 1.4 petrol doesn't seem to be that much less economical than the 1.6 diesel.
The paintwork on my old 2011 car was suspect in places, it looked very thin on certain edges like along the front edge of the rear doors and around the top edges of the tail-gate. It's not bubbling up or flaking off, but it has an orange tint to it as though surface rust is showing through the paint. The spray coverage on my car may have been patchy, I don't know whether it's a common fault, but check those edges on any cars you look at. The mid-spec models add air-con, electric windows and alloy wheels, so check the air-con is working, and also what state the alloys are in. The original wheels aren't great, they are prone to corrosion.
My old car has now done about 205,000 miles and has been very reliable. The engine hasn't been touched, it still has the original clutch, exhaust system. Other than replacing wear and tear items like the brakes, the only parts I've had to replace are front suspension drop-links, rear shock absorbers, a couple of aux drive belts, battery (twice), and a rear brake shield which rusted away. A competent DIY mechanic can keep on top of the maintenance, especially with the help of this forum. It has blown quite a few headlamp bulbs, though since changing to long-life bulbs that has been less frequent.
When I bought the car on a PCP in 2011, I had to include for full maintenance package, and one reason I picked the i30 was that the cost of the maintenance package was a fair bit lower than similar cars like the Ford Focus I had previously.
As with any used car, try and find one that has been looked after. Check the MoT history on-line to see if it regularly passes the MoT. If it has a history of failing tests and requiring work before being passed, that would be a sign of neglect. For many cars, the only time they get any attention is at an MoT when the owner has no choice but to fix it. If they are likely to present a car for an MoT with blown bulbs, bald tyres, perished wiper blades and inefficient brakes, what confidence can you have that they have been getting regular maintenance done (like changing the oil)?
