Nothing major or overly expensive yet.
Had a new alternator, water and oil pumps fitted shortly after I had it to fix a mysterious rattling under the bonnet. Oil and water pumps would have been cheap had I dared to fix them myself! Good job I did it - it was the water pump, which if it crumbled would have snapped the timing belt and sent the pistons through the bonnet.
Distributor packed in last year due to muggins here not fitting the cap back on properly. (I was curious as to if it was a standard dizzy, coz the car's got fuel-injection). Dampness must have leaked in before I noticed, and corroded the insides of it over time. *the embarrassment!*
Had a minor coolant leak and the cooling-fan thermostat recently went.
All in all nothing particularly expensive. If you think about it, all that went wrong was a coolant leak, thermostat and water pump. The rest was either diagnostics (oil pump, alternator), or caused by me (distributor).
Well, it's the only petrol-engine I know of that's good for a third of a million miles! Current one has only done 130k, but the last did 300k and it took a wall to put an end to it! The robustness is very impressive for a small, cheap petrol car.
It's a bit boring, but a comfortable happy motorway mile-muncher, getting about 51mpg on the motorway and 42 about town. This drops to 38 if you thrash the nuts off it.
The 1400 cfi or carb models are nothing short of asthmatic in their performance, which is why I opted for a multi-point (82hp) version, which is exactly the same unit, but with a better inlet-manifold. Off the lights, you'd swear it was a 1.6 or even a 1.8 of a similar age, but its 3rd and 4th gear performance is a bit disappointing, which is frustrating on A-roads.
Change the oil regularly and it will pass its emissions every time, even after obscene amounts of mileage! Similarly, I've noticed that the timing and alternator belts wear quickly, so consider changing these at each service (it's not very expensive, and considering the fact that the car costs virtually nothing to run, you may as well spend the few quid to do it).
The handling is positively atrocious, particularly in the wet. Expect to have understeering at low speeds, leading to the back-end sliding out, -seeing your own brake-lights as you go sideways around roundabouts is a bit unnerving.
Very good corrosion-resistance, although the rear wheel-arches are starting to bubble and feather. Doesn't really bother me - it's only on a single-skinned bit so it's nothing a little body-filler or cheap and easy welding can't fix, and it's only aesthetics. Considering it's never been garaged in it's life you can't complain!
All in all, it's the cheapest car to run I know of. You can do insane mileage on one engine without a rebuild, unbelievable fuel economy, and nothing ever seems to break on it. Apart from the fact it's a bit slow, basic and boring, I can't fault it.