[usrusr]

So this only reduces inefficiency while the the engine revs too low for the turbo to kick in? Then it is competing with electrically assisted turbocharging (spin the turbo electrically when there is not enough exhaust pressure, basically a super/turbo hybrid using electric transmission), as both are addressing the same inefficiency.

I know where I would put my bets in terms of price, reliability and ease of development.

[hvidgaard]

At lower revs the turbo is more likely to boost the engine if you demand power, of course depending on the dimensions of the turbo, but it doesn't make sense to put a performance turbo that works in the upper rpm range, in a regular car.

In any case, an electrically assisted turbo is not a replacement for this. This is a way to have high compression at low loads, such as highway crusing, and ability to lower compression when boost is needed for performance.

[sandworm101]

>> while the the engine revs too low for the turbo to kick in?

This is a common misconception of 'turbo lag'. A modern turbo is actually operating at the low revs too. The boost is there. But a modern turbo engine, especially a diesel, has a very narrow powerband, giving the impression that the turbo isn't active until higher rpms. This isn't real 'turbo lag'. Real 'turbo lag' is the delay caused by the fact that the turbo depends on exhaust pressures, which rise only momentarily after throttle increases. But this problem has largely been solved via mutli-stage turbos, lighter turbo parts, waste gates and the like. Real turbo lag, where it is noticeable, occurs at all rpm ranges.

[LoSboccacc]

Which models are coming out with electrically assisted turbos?

[stonewhite]

Audi SQ7 is coming up with an electrical supercharger and two sequential turbochargers to deliver lagless and variable boost for high performance in all of the rev range.

http://www.caranddriver.com/news/2017-audi-sq7-tdi-diesel-ph...