I can remember when cars were scrapped because their bodywork was rotten. Sometimes it took just 10 years from new, which meant that often the rest of the car was still working fine.

So isn’t it ironic that now we have bodyshells that last for 20 years and more, we still scrap some cars much sooner because they’ve become uneconomic to repair. How did this happen?

Don’t blame the car makers: they just make the products we asked for, within the constraints laid down by governments. We want better fuel economy, greater performance, improved refinement, extended service intervals and more features to play with. The politicians want cars that cause fewer deaths and injuries, emit fewer toxic gases and contribute less to climate change through CO2 emissions.

So hemmed in on all sides, engineers develop clever solutions to keep everybody happy. You can now have a car that’s just as powerful as your old one but safer, less polluting, more economical, more refined and better equipped. But there’s a catch.

There’s no magic wand. The way engineers meet all the conflicting challenges is by developing more complex engines, transmissions, electrical systems and other stuff, usually computer controlled and driven by software.

The downside for car owners is not so much a reliability question – today’s improved quality procedures and manufacturing methods tend to look after that. The problem is the cost of repair a few years down the line. Ownership costs during the early vehicle life tend to be low, apart from depreciation, but as the car gets older, the huge cost of repairs can end its economic life long before it’s physically worn out.

This doesn’t just apply to ‘fancy’ models from premium brands. If you drive a four-cylinder diesel, it’s probably got a dual mass flywheel (DMF) to make it smoother. They don’t last forever and the bill is usually over £1000 for a replacement. Suddenly that £1500 car doesn’t seem such a bargain.

Faulty engine management systems can cost over £1000 to replace, plus the cost of diagnosis, then there’s the airbag systems, the anti-lock brakes, the catalytic converter and its sensors. Even the design of the rear suspension can affect long term ownership costs: that complex multi-link design that won so much praise in the press for good roadholding, ride comfort and low noise doesn’t look so clever when you face a bill for replacing all the bushes, due to wear.

I’ve had personal experience of the downside that comes from all this complexity, on a car just a few months old. A fault that would have been trivial once over (a poor connection between a spark plug lead and its ignition coil) caused the engine management system to warn me ‘do not drive vehicle’, meaning a long wait for a tow truck. This is not progress.

So are we condemned to scrapping otherwise useful cars, because of some failed component that’s too expensive to replace? It seems sad that we’ve just swapped the corrosion problem for a complexity issue.