How much did you pay the last time you took a car to be serviced at a main dealer? £200 or perhaps £300? How does £121 sound? That’s what I paid my local Renault dealer for the last annual service on my Fluence electric car – and even that was for the “big” service, which alternates with the £80 or so “small” service.

It’s not surprising it was cheap. The service schedule that accompanied my bill consisted mainly of the sort of straightforward checks any responsible car owner should carry out regularly anyway – fluid levels and tyre tread depths and so on. There were no charges, of course, for items like new spark plugs or oil changes, or their associated labour costs.

Not only that, but at seven years old, my Fluence is now entering the stage of life when, if anything, the advantages of electric over petrol or diesel may be getting bigger rather than smaller. Owners of older electric vehicles don’t need to worry about when they will need their first replacement clutch or exhaust, to take just two examples.

And the advantage of electric vehicles in terms of servicing and maintenance costs is growing. Fleet Assist, which advises companies in the fleet industry, has identified a number of cases of manufacturers shortening the servicing intervals on the latest diesel models that have been designed to comply with the latest toughened up World Harmonised Light Vehicle Test Procedure emissions standards.

With electric cars differing so much from petrol and diesel cars in their servicing requirements, the question arises about whether traditional dealerships and standard servicing schedules are the best way of supporting these cars. Certainly Tesla, the first all-electric manufacturer to sell cars in significant volumes, has started to move away from annual or mileage-based servicing to an “as required” approach, as well as making extensive use of “over-the-air” updates. The company has, in any case, always had a less extensive network of dealers than other manufacturers, which is more noticeable now that its cars are selling in bigger numbers. Tesla has also offered a we-come-to-you mobile service for some jobs, although I don’t suppose that would work for all servicing and repairs – every decent mechanic I’ve ever met seems to set great store by lifting older cars, in particular, in order to assess their true condition by having a good poke around underneath.

These trends pose some uncomfortable questions for the main car makers. Will they have to shrink their dealer networks as cars need less and less servicing? Complicated plug-in hybrids may keep them busy for a bit, and I suspect older electric cars will stay with franchised dealers for longer than petrol and diesel cars because of the lack of qualified independent alternatives, but I doubt the day of reckoning can be postponed for ever.

The financial case for electric has always, of course, depended on a trade-off between high initial prices and very low running costs – and not just cheaper servicing, but zero vehicle excise duty and negligible fuel costs when charging from the domestic mains as well. The problem has been that a lot of buyers haven’t been able to see beyond the high up-front cost to the big savings beyond.

But even this established trade-off is now tilting ever more strongly towards electric cars, because they are becoming cheaper to make as well as to maintain. Researchers at Bloomberg New Energy Finance (BNEF) estimated in 2017 that electric cars would be price-competitive with their petrol and diesel counterparts by 2026. Last year, the same team were predicting price parity by 2024, and this year, they have brought the date forward to 2022.

The main driver behind the trend is the rapidly falling cost of batteries. BNEF estimated that in 2015, the battery pack accounted for 57 per cent of the value of a mid-sized US-market electric car. But this year the battery pack is calculated to account for only 33 per cent of the vehicle’s value, a proportion that is expected to decline to just 20 per cent by 2025.

So, within a few years, electric cars are going to be both cheaper to buy and run than petrol or diesel cars. Add in the other advantages – smoothness, quietness, ease of operation and lively performance – and the big switchover to EVs seems to be unstoppable, as long as the industry can make enough of them, and that’s a big worry right now.

David Wilkins