You might be thinking of VVT or variable valve timing, which changes when the valve opens. Variable valve duration changes for how long it opens for and I think is a recent innovation. The latter allows for more efficiency as the engine at different speeds and loads requires more or less lift duration. It's also continuously variable across the RPM/load table, wheras most VVT systems just swap between two different activation timings and as such are always a compromise somewhere in the range.

I have also seen a system that swaps between two different cam lobes entirely, offering two different cam profiles which can also vary valve duration and not just timing, but you're limited to two settings again, where these newer systems offer complete variability.

No, these are not VVT.

I might be misremembering, but I thought the new bmw system was dual cam - so exactly what you are suggesting, a trade off in the middle, but not vvt.

At any rate, variable cam systems in bikes have certainly been around since the early 80s with one of the 400c cbrs. They never really caught on but there are a bunch of variations.

I should have been more explicit, but above is not incorrect.

Honda had VTEC engines even back in the 80s, they physically choose between (three, if I recall correctly) cams.

These are not pure VVT systems, although they are not continuous like the Hyundai.

Not with variable duration. Hyundai is the only car company doing that now.

Worth noting that Rover apparently had a VVC system [1] that allowed the duration of intake valves to be continuously varied all the way back in 1995.

[1]: https://www.autozine.org/technical_school/engine/vvt_4.htm

Like I noted, not the same as they hyundai system, but not VVT either. And bikes, not cars.