Then again, Superchargers are more than just fancy plug-in points: they're also a business model in which electricity is given away "free for life" for Model S owners, with all costs factored into the upfront price of the car. Musk is very clear that other EV makers would have to subscribe to this same business model if they want to partner up. They'd also have to contribute a "fair" proportion to the maintenance and running costs of the ever-expanding Supercharger network itself -- costs which he insists aren't very onerous, especially since the physical locations are often given to Tesla rent-free, and in some cases they're powered by solar panels. Rival companies might turn their noses up, of course, and in fact they're already battling over alternative charging standards, but it's clear that the offer is there if they want it.

Update: Tesla's PR people have been in touch to clarify a couple of things. Firstly, although the company is indeed offering to share its charging and adapter specifications with other manufacturers, on the conditions described above, this won't necessarily involve sharing patents. Secondly, some sort of "patent giveaway" or "patent release" is still on the cards, but the company isn't quite ready to announce the details just yet.

Here's a quote of what Elon Musk said at the UK event, after being asked a question on this topic by Stuart Miles of Pocket-lint:

Journalist: You talked earlier in the week about sharing patent technology. You hinted at that during a BBC interview yesterday.

Musk: Right.

Journalist: Is that sort of aimed towards the superchargers and allowing other car manufacturers to use your charger network?

Musk: That was already said. Actually we've already said that. The intent of the Supercharger network is not to create a walled garden. Any other manufacturer that's interested in using them, we'd be happy to accommodate. It's just that they need to be able to accept the power level of the Superchargers, which is currently 135kW and rising, so any car needs to meet the Supercharger standard. And they'd also need to agree with the business model, which is we don't charge people on a per-charge basis. They'd need to contribute to the capital costs proportional to their fleet's usage of the network. So we think that's pretty fair.