If you’d believed the hype around the first batch of autonomous concepts a decade or so ago, you’d have expected to be being driven home from the pub by now in a truly driverless car with no steering wheel.

Yet the mood has long since shifted, and now a line has been drawn between driver-assistance technology and true autonomy that cars seem unlikely to ever cross - for many reasons, but perhaps chiefly the legislative nightmare they open up and the funding they require. 

The idea of solid-state technology as a means of bringing down the cost and weight of EV batteries – while improving range, power density and resistance to degradation – has been around even longer than any serious discussion about autonomous cars.

You can date solid-state chat right back to when the first wave of mass-produced EVs arrived at the start of the last decade.

Toyota, Nissan, Honda, Volkswagen have all recently confirmed various developments to their roll-out of the technology, with the former two both firmly (and repeatedly) committing to 2028 as the year when it will go on sale. 

Unlike autonomous cars, then, it seems the day for solid-state batteries is on the horizon.

Or is it? Mercedes-Benz technical chief Markus Schäfer believes the all-out replacement of liquid lithium ion battery technology with solid-state chemistry in future EVs is most definitely not a given.

When the original proclamations were made around existing lithium ion batteries, they were done so without the knowledge and foresight of so many of the brightest brains from all across the world working on developing the technology for so long. 

Schäfer said work has been intensifying on existing liquid electrolyte lithium ion battery technology and there has been “unexpected” progress with the technology, to the point that it could end up being “neck and neck” with solid-state technology in terms of cost and energy density. 

Given that a whole supply and production network has been built up already for the existing battery technology, why would a new one need to be built up again for solid-state technology?

Nissan has said that new factories could even be needed for solid-state EVs, because the impact on almost every element of development and manufacturing is so dramatic. 

“When you commit to something like solid-state, you have to change the whole mechanism and architecture of the vehicle,” David Moss, Nissan’s senior vice-president for R&D in Europe, told me last year. 

Forget battery-electric versus hydrogen in cars: that race has been won by the former. Now what’s up for debate is which battery technology will power them, and it’s a debate with huge interest clearly attached, as Schäfer’s comments last week made for the most popular story on autocar.co.uk so far this year. 

So who’s right? Well, Schäfer’s notion that solid-state “reminds me a little bit of the forecasting for autonomous driving” makes it clear which side of the fence he’s on.