A month ago one of the family fleet, a 1992 Renault Alpine GTA V6 Turbo, developed a misfire that was so significant that it became practically undriveable.

I'd tracked the fault to the ignition side of things so, instead of messing around, I decided to replace virtually the whole system. All of the existing parts were of an unknown quantity and, although some initial diagnosis suggested the coil and control module to be the root of the issue, I didn't want to end up chasing problems through a series of old components.

The Renault's ignition system isn't overly powerful either, and lighting off those highly pressurised combustion chambers requires a reliable and strong spark, so it was worth spending the money to make it all perfect.

A new ignition coil and control module were first on my shopping list, but searching around revealed that a replacement item for our particular GTA would cost £184. That seemed a lot, especially considering that the coil didn't look overly special.

Some Alpine specialists gave me some suggestions as to where to find cheaper ones but, even after trawling the web and forums for a few hours, I was still none the wiser. Mainstream suppliers predictably didn't have anything to offer, while a few alternatives looked like they'd end up doing nothing but being sent back.

It was then that I referred back to the car, took the actual part number off the ignition coil and searched the web for it. Voila. Instantly I managed to match it with the same coil that was used on several different cars, all of which were much more commonplace. The result? A new coil, identical to the original one but without the Alpine markup, for £87. That's a saving of almost £100, plus I'd have a part which I knew would fit and operate as expected.

Tracking down suitable spark plugs - six NGK BP7EFVX platinum-tipped items - proved easy. After searching around I found an independent website selling them for £6.43 each, including VAT. Look elsewhere and they could cost you £10.83 a piece. That'd set you back £64.98 instead of £38.58; that's £26.40 more overall, a hike in cost of over 68 per cent.

Admittedly the plugs I found weren't the cheapest I'd seen, but I trusted the supplier and - more importantly - they were actually in stock. I'd rather pay a little extra and get what I wanted, rather than ending up with several mismatched plugs a few weeks later, or simply nothing at all.

Cross-referencing the part numbers of the supposedly no longer available distributor and rotor cap revealed them to be the same as that found on BMW's M30 'big six' engine; components that are still available. They weren't cheap though, with the cap costing £54 and the rotor £18, but they appeared to be produced to a high standard.

So, for £197.58 in parts I'd refreshed everything that was potentially at fault in the Renault's ignition system. If I hadn't searched around, the same selection of parts could have cost me up to £321, so I'd saved myself over £123. If I'd had more spare time I might have been able to make an even bigger saving.

Sometimes you just need parts in a rush, at any cost. If you've got a minute to look at the part numbers and do a bit of research, however, you could save yourself hundreds of pounds.

What will I be doing with the money I saved? Spending it on more car parts, of course - probably a set of HT leads. Those are the only things left to renew in the Renault's ignition system, but I'd like to fit some uprated items and that means finding out the maximum diameter of lead that will fit in the turbocharged V6's ignition lead trays first.

Have you ever made a major saving from doing a bit of research and cross-referencing? If so, post below and tell me about it.