Originally Posted By: A_Harman
Camless valvetrains have been worked on since the mid-70's (that I know of). Either electric or hydaulic actuation systems have been considered, but they never really deliver on the promise of incredible fuel economy. Too much parasitic loss for the pumping work benefit that you get. And a lot of technical risk, too. If the engine loses sync once in its life, and the ECU opens valves at the wrong time, it's a major failure. But the list of different operating modes that could be done with camless is mind-boggling.
Which is why systems like MultiAir are so successful. The cam is retained, but it only defines the "outer envelope" of the valve profile, so to speak. Within that envelope, clever hydraulics allow infinite lift and duration variability. Its still all powered by the cam, the hydraulics are able to rapidly capture and release valve lifting energy from the cam as needed.