0: http://blog.caranddriver.com/koenigseggs-camshaft-less-engin...
They've been working on camless valve actuation for decades. I read an article about a prototype system back in 1992. The article then said that the power requirements of the solenoids was a big problem. I'm not sure what the problem is these days. As you noted, Koenigsegg has a working prototype in an actual car (not on a test stand, connected to mains power, like the one in the article in 1992), and it seems to work fine. There's probably some kind of problems with reliability.
Yes, reliability is probably the issue. However, the same could have been said about EFI back in the day.
Full camless engine design is something we may only see in high-end racing and supercar applications for while yet.
Back in 1992, making an electric car like the Tesla probably wouldn't have worked out too well. Instead of an electronically driven induction motor (or a 3-phase brushless motor as some other vehicles probably use, also electronically commutated), they would have had to use a brushed DC motor which isn't so great for longevity or efficiency, because the electronics needed for the better motors would have been too expensive, bulky, and inefficient. Now, DC brushed motors are all but obsolete except for small, cheap applications like <$50 power tools.
The same might have been an issue with those camless valves: actuating those solenoids precisely probably required some serious power electronics capable of supplying and switching high currents at very high speeds. Modern power electronics are good at that now.
I wonder if one problem isn't control of the valve speed. If the solenoid is moving too fast, that'll wear the valve seat much faster (in a regular cam engine, the valves don't shut that quickly at low rpms because the valve profile prevents it). In a cam-less engine, the solenoids would effectively be going full speed all the time, meaning more valve seat wear from slamming shut so hard. This makes tuning engines easier perhaps (more digital-like operation: on/off), but increased wear is bad for something you want to last for hundreds of thousands of miles with no service. So they might be looking for a way to control the actuation speed of the valves, and vary it with engine speed as cams do now. That means even more complex power electronics.
The alternative is to just not design for high RPM; the most efficient internal combustion engines are huge low-speed two-stroke diesels used for ships and stationary generators.
Then again a single piston in the marine engine weighs 2x of an entire car so they can easily do things that one wouldn't bother to do on a smaller engine.
No, they don't. 750rpm is pretty typical these days. They'll idle at higher speeds when cold, though, to warm up faster.
This isn't as bad as you might think, because of the nature of springs. When the valve closes again, most of the energy spent compressing the spring is returned to the engine!
I was referring to full-on solenoid control of valves without needing cams at all.