No, this does not mean that the four-stroke engine has no valves, but that the valves are 'free', e.g. from the forced control by the camshaft(s). Remember, with these, their actuation would also be omitted including timing belt or chain. It would be fully variable control without the hassle of BMW, for example.

However, one possible advantage must be conceded from the outset, namely that the engines might not build as tall. Namely, that is exactly what they do because of the complicated attachment above the valves. The valve springs also remain for the time being. There is already a forced control in the experimental stage by Camcon Automotive from England.

It is perhaps the real problem, that this development, however small its field of application, is probably too late. Because in the end, even it could not save the internal combustion engine from eternal damnation. For one thing must be clear, the hurdles are high and perhaps Koenigsegg's approach is just a release of a development that has been put on hold.

After all, it is by no means the first attempt to bring something like this into large-scale production. And German suppliers were also involved, such as Schaeffler. A little of the idea is part of Fiat's multi-air process. Here, however, only the intake camshaft is saved, which means much less than half the distance travelled.

Multi-Air goes back to the once cultivated cooperation between General Motors and Fiat. It cannot have been very successful, because GM later paid a lot of money to get out of the contracts with Fiat. They also tried the principle on larger than Fiat's later two-cylinder-only one themselves and in the end discarded it.

Actually, the function is explained quite quickly. The exhaust camshaft also receives the cams for the intake valves. These actuate small pistons, which in turn send oil to further pistons on top of the intake valves. Now you might ask what the advantage is over, say, a conventional, mechanical linkage.

There is a kind of oil drain valve in the line, which makes it possible to control the valve stroke and thus, of course, the opening times. In this way, one hoped to get rid of the throttle valve, for example. Did they got rid of it? No, but they claim that it is mostly open, which shows how difficult it is to achieve a fine-grained control of the oil flows up to idle.

I asked the two Schaeffler engineers involved with this why they had not developed it further at that time. The answer was sobering. A tremendous amount of development work still lay ahead of them. And so the Fiat engine and the one in the Alfa Mito remain advertising gags for being different. Despite extreme downsizing in the former, no significant progress can be seen in the consumption.

One could almost make bets that it won't just be multi-air that disappears once Stellantis' rationalisation measures take hold.

As I said, it's not even halfway there, making it even more complicated than conventional engine control. Just how big the problems are is shown by Koenigsegg's approach, which instead of oil hydraulics uses pneumatics Instead of oil hydraulics, pneumatics for the actual opening and closing of the valves, which might be readily available for trucks, but would hardly be so readily available for cars.

The technology has allegedly been realised in the Gemera. Previously, it had been tried out on an old Saab for 60,000 km. Air opens against and closes with the valve springs. The whole thing is controlled by sensors that e.g. the position of the valves to the control unit. The question is whether the Gemera is really a tough test, since it is supported by three electric motors, so it presumably does not have to cover all operating ranges independently.