I have owned my Tigra Verde for 2 years now, and fortunatly had no major problems other than,
Faulty Indicator stalk that flicks on the high beams when the indicator switches off. Still not fixed.
Window washer motor recently packed in. but other than that it has just done 101,000 miles and just had its second cam belt fitted, very reliable, I must admit I am 5"11 and can fit comfortable within the car, but if you have to wear suits to work and spend up to 2hours a day in traffic its not comfortable at all, but I love the car its fun to drive and has a good amount of power when you need it.
I've had my Vauxhall Tigra for over a year now, and have not really had any problems apart from usual car stuff.
Things like changing the cam belt, light bulbs, exhausts, tyres, etc. These are just normal everyday servicing costs and part of running a second hand car. For sure, changing the cam belt every 20-30k or 2 years is quite a lot, but every car needs this done and most cars are around this interval. If you don't then you take your chances.
I've changed the cam belt + tensionser and water pump (driven from the cam belt) on mine as I don't know when it was last done to be safe.
For the comments on indicator stalks flicking into high beam. Mine did that; it's just the stalk getting worn over time. Mine was doing that at 80k miles and I bought a replacement from a scrap yard for £5. It just clips on, so took about 3 minutes to change. Easy to do yourself and easy for any garage to do to.
If the engine management light is coming on it could be the connectors to the sensors. Easy way to clean them is to get some fine sandpaper and go round the engine and unplug each sensor connector (one at a time so you don't forget the order!). Rub the fine sandpaper on the connectors blades to clean of any corrosion. Plug it back in and move onto the next one.
This will cure an awful lot of these type of problems as that is what that light means - it's just the engine saying *in you best little car voice* "I can't see one of the sensors - please check the connectors and wires for me!"
Pain in the backside, but again something that is not uncommon on all cars over a certain age.
Just my 2p worth.
I think they are great little cars for the money and look different. Great if you're a couple and don't need to take passengers. Don't even consider them if you need to transport adults in the back. I had 3 in the back recently, and I needed a crowbar to get them out, they were so wedged in!!!