Must I play this 'car repair lottery'?

HELPDESK:Answering all your motoring queries

From RQ: My 2004 Opel Vectra developed a fault where it can suddenly and unexpectedly lose all throttle control. If this happens the ignition needs to be turned off and back on again, at which point I regain throttle control. This can be a hair-raising experience.

I left the car with the dealer and was told later that the issue lay with one of the following: the throttle pedal position sensor; the throttle body; the engine control unit (ECU).

They were 90 per cent certain that replacing the throttle pedal position sensor would resolve the issue and charged me €463. Within 24 hours the issue occurred again so I left the car back with the dealer. Later that day I was told that the issue must lie with either the throttle body or the ECU and that I could take my pick of which one to have replaced next.

Now I’m sure you can see where this is going. If I pick wrong then I will spend more money replacing another part that is not broken. They were kind enough to give me a quote to have both parts replaced (the “worst case scenario”): throttle body €586.50; ECU €774.50; labour €250. Taxes make up another €217.

It does seem to lay the onus unfairly on the owner to play some sort of car repair lottery. I have heard of situations similar to this arising, where the diagnostic equipment fails to show up any problem so mechanics must work through the various potential issues involved. In most cases, however, it would be normal to temporarily replace parts until the problem is rectified but in this case it seems that you must buy new parts along the way.

An Opel Ireland spokeswoman said: “Most car problems, as you know, get resolved through our highly skilled Opel-trained technicians. However, sometimes diagnostic equipment cannot always ascertain the root cause of the problem. On these rare occasions, a process of elimination may have to be followed if the problem is not easily identifiable. As a gesture of goodwill, we will take the car into one of our Opel regional technical centres to identify the root cause of the problem.”

From DB: After 20 years of driving the family taxi, I’m looking for a smaller coupé sort of car that looks good but still has a back seat in case I have to carry passengers. I also need a decent boot for golf clubs. I’ve €20,000 to spend and while my mileage is small, I’d probably hold onto it for six or seven years. I don’t want it to be so flash that it will go out of date by next year. Any suggestions?

The last part of your query is perhaps the most important, for a lot of coupés look dated within months of launch. With this budget you are probably looking at the used car market. It’s littered with cars ranging from the mildly tempting to the boyhood dreams, but I suggest that unless you are willing to put in the time – and the undoubted investment – stay away from the likes of a classic Porsche or hot hatch coupé.

I also have some qualms about the long-term reliability of cars with multiple-part folding metal roofs, which were particularly popular with car firms in the middle of the last decade.

One car springs to mind: a BMW 3 Series coupé. The boot is big enough for your clubs, there are plenty of them on the market so you can get a good price, and the diesel version will ensure that, should motor tax rises feature in any upcoming budgets, you won’t be as badly hit as others. We saw several used coupés that fit the bill within your budget, usually registered in 2007 or 2008.

Send your queries to Motors Helpdesk, The Irish Times , Tara Street, Dublin 2 or e-mail motorshelp@irishtimes.com