As it happens, my car is a V6. but I'm wanting here to mention the 'upgrading' of Internet Protocol to permit wider access.
Back when Vint Cerf and Robert E. Kahn developed the 'new' "Internet Protocol" to enable machines to connect to each other (replacing the old point-to-point method) they came up with the idea of assigning an "Internet Address" to each one.
It was a 32-bit number and is nowadays usually written as something like "123.45.67.89". It works pretty well and domain names – such as alisonw.uk – get converted into one of these numbers, as does the machine you are reading this on.
Thing is, that design (actually 'IPv4' but the first one to become widespread) created a limit on the numbers of machines which could be connected to the internet at one time. 4,294,967,296 of them – which is a whole lot of computers, clearly! And in 1980 it was thought (quite reasonably) that the idea there would be more than four and a quarter billion computers on the internet would have been considered completely crazy. But now, almost thirty years on, we are connecting mobile phones, netbooks, IP telephones, webcams, even toasters and refridgerators directly to the internet – and in many cases keeping them online 24 hours a day, not giving others an opportunity to use the same number – so that 4,294,967,296 † just won't be enough anymore. Indeed, ARIN ( American Registry for Internet Numbers) reckon they'll run out next year!
So a few years back – ten, to be precise – a new numbering system was created. IPv6, as it became known, allows for massively more 'things' to be connected at the same time. In total it would be possible for just over 340,000,000,000,000,000,000,000,000,000,000,000,000 computers, phones, televisions, mobiles, whatever to be online at the same moment. That is 37 zeroes, by the way, or roughly 4,500,000,000,000,000 for every known star in the universe. So plenty of room for expansion without, one hopes, having to go through another redesign for an awfully long time.
But one of the issues about IPv6 from a server room or end-user viewpoint is that it is rather like the switch from analogue to digital television, or from VHS tape recording to DVD burning. Some of the kit can be made to work on both, but often software or hardware changes or additions are required to utilise the new IPv6 properly. And once you've moved on you can't then plug back into the old again. Most computers now will work on both, but most mobile phones. And the networking kit – the routers, modems, switches – quite probably won't unless they are very recent (or very expensive). So not only does the intermediate equipment all have to be upgraded (ie. replaced) but also how to get the new and the not-so-new-but-still-connected stuff to talk to each other needs to be sorted out. Disruption of the internet then is pretty much guaranteed. When? about three to five years, probably.
I recently upgraded the network kit in my server room and thought I had spec'd IPv6 capable kit throughout. It was only afterwards I discovered misleading marketing in that the ADSL router considered "IPv6 capable" as meaning "IPv6 on the internal can be converted to an IPv4 tunnel outside" which is, of course, pretty useless if you wanted native IPv6 on both sides.
One also has to consider the major rewrites of code (and database schemas) in moving from v4 to v6 nomenclature. And how many systems are embedded or non-upgradeable? How mission-critical are they? Is it more cost-effective to keep them - at the risk of degraded network performance overall - rather than replace them to take advantage of the IPv6 opportunities.
IPv6 was created ten years ago, and most of the internet backbone already supports it. Your ISP though is probably still working out how to provide it to you – and when. Yes, it will come, indeed it has to come, but "when" is a financial decision as much as a a technical one.
† Actually, not all of those are available for use as some are reserved for special uses, and every router in the chain between you and the site you want to use also requires an address.