I took an old Becker navigation device out of my mother's car this weekend.

There is nothing fundamentally wrong with it. The hardware still works perfectly. The screen lights up, the buttons respond and it would probably continue doing its job for years. The problem is much simpler. I cannot find the original software anymore. Becker is gone, the download site has disappeared and something that could probably be fixed in a few minutes has effectively become electronic waste.

It made me wonder whether we are asking the wrong questions about electric vehicles.

For years the discussion has focused on batteries. Will they last? How much capacity will they lose? What happens after ten years? Increasingly, I think software will become the much bigger issue.

A car bought today may still have perfectly usable motors, batteries and suspension in ten years' time. But what happens if the navigation is no longer supported? What if the user interface feels ten years old? What if the driver assistance systems never improve because the manufacturer has already moved on to the next platform?

Residual values have always depended on mechanical condition. In the future they may depend just as much on digital condition.

Perhaps the used-car market of tomorrow will not ask first how healthy the battery is.

It will ask whether somebody still cares enough to maintain the software.

That feels like a much more important question.