[serialk11r]

I feel like it's kind of not worth it on a hybrid, because on a hybrid car you can just shut off the engine at low load, and use heavy EGR dilution for medium load. Cooled EGR is still good for efficiency.

Then again, Honda puts VTEC on every engine despite the added expense.

I'm not sure if it can improve cold starts, I can't really think of a reason why it would. I suppose you might have some fuel air mix floating around the intake tract that's kind of getting constantly pumped back and forth across the valve, giving it more time to mix with the air, or maybe it just means more fuel sticks to the walls and actually makes things worse.

I think Koenigsegg is full of crap when he says you can use port injection, direct injection is basically always better...

It is useful on a turbo engine for response and efficiency reasons: Say the engine is knock limited at full VE and 1 bar boost. You can immediately go max VE while the turbo is spooling, then as the turbo pressure builds past 1 bar, increase duration to limit torque instead of using the wastegate, and you have a much more efficient engine. This lets you use a higher CR with an intercooler, since the intercooler is rejecting more heat. Porsche does this with a low VE intake on their GT2, basically letting the turbo do more of the work.

The other type of engine it's useful for is the one I described, a high revving NA engine. No more valvetrain problems or low end torque to worry about, only getting the bottom end to hold together at whatever speed you choose.