Volvo does appear to be distinguishing themselves though. Namely in the fact that they're coming to market with an e-booster (electric turbo). There are plenty of dual-inlet turbocharged engines on the market, and Mercedes pushed the envelope with their M133 engine found in their performance oriented version of the CLA, but no one, that I'm aware of, has brought an e-booster to market. There was quite a bit of speculation that BMW would use one on their latest M3, but instead they went with a dual-turbo setup and some cool electronic wastegate management software that improves spool-up time.
The combo supercharger/turbochargers setup is crazy exciting though. The last car I can remember with that kind of setup was Lancia's group B rallye submission, the Delta S4. That car made, ostensibly, 480 HP from about 1.8L. In reality, the output was more in the area of 550 HP, and legend has it that engineers pushed the powerplant close to 1000 HP.
Every auto manufacturer is staring down a future of emissions and fuel economy standards that are going to require some fundamental shifts in the way cars are built and powered. Most manufacturers are moving in the direction of hybrid technology. BMW is betting the farm on mass-produced carbon fiber technology. Everyone has a strategy, and most involve lower displacement, forced-induction engines, often coupled with hybrid drivetrain components.
Volvo is driving a third turbine, which works, but it's not as efficient as simply spinning the turbine directly with an electrical motor assist. The reason they don't do this is that exhaust powered turbochargers are a real motherfucker of an environment. Excuse the language, but they really are. A turbocharger glows red-hot when generating boost. Putting an electric motor anywhere near them requires lots of advanced materials science and engineering.
A turbocharger has two main parts: a turbine that is powered by exhaust energy, and a compressor that pressurizes the intake manifold. Volumetrically, these two are separate. They are connected mechanically by a shaft that runs between the turbine and the compressor. This shaft is, traditionally, only a few inches long, and has some pretty sophisticated lubrication systems.
Mercedes went all crazy with their F1 engine and spaced the turbine and compressor apart. Way apart. On opposite ends of the engine apart. This is crazy when you consider how fast a turbo spins. It's not unusual for them to exceed 100,000 RPM. The shaft must be lubricated and extremely well balanced. The benefit of this arrangement is that the compressor is not exposed to the heat of the turbine. As I alluded to earlier, the KERS system in an F1 car can drive the turbocharger directly using electrical energy that is recovered during braking. Spacing the turbine away from the compressor affords the perfect opportunity to save the life of your electrical motor that drives said turbo.
The hope is (and it always is) that this technology will trickle down to road cars. Volvo appears to be taking the first step, albeit with a compromise.
The addition of the supercharger to the turbo dramatically improves low RPM power and often peak torque as well. In doing so, it also makes a larger turbo more practical as it reduces the problem of "turbo lag" (wherein a large turbo paired with a small engine doesn't engage until very high RPM)
Race engines, of course, often aren't quite as worried about turbo lag because many cars spend their entire time at peak power.
Except for all the auto enthusiasts that Audi (ur-Quattro and almost all their performance cars since), Toyota (Celica GT-R, Supra), Nissan (Skyline GT-R), Subaru (pretty much everything), court, or who remember the era of 1000 HP Formula 1 cars fondly.
But yeah, I guess all automotive enthusiasts.
"The 2016 XC90 (on sale early next year) is the first of this new generation of Volvos. It’s powered by a 2.0-liter four-cylinder engine with a turbocharger and a supercharger. (While the turbo works best when the engine’s already going, a supercharger forces in air with power generated by the engine itself, so increased boost is available from idle.) The supercharger runs from idle to 3,500 RPM. Above that, an integrated clutch disengages the supercharger, allowing the turbocharger to take over."
Based ont his paragraph, it sounds like a traditional supercharger that works up to 3,500 RPM. Later on though, we get this bit:
"We’ve seen plenty of twin-turbos before. Volvo’s innovation is adding a third—third!—turbo. But this one doesn’t charge the engine. It charges the other turbos. It’s electric, hence the name “e-booster,” and sends air into the two conventional turbos to improve their performance below 3,300 RPM, filling out the torque curve and eliminating that pesky lag problem."
Now we have an e-booster referred to as a third turbo, which runs up to 3,300 RPM.
So, the confusion is warranted. The article isn't entirely clear on whether these are two engine options, or a single engine with inconsistent details.
-A prototype with 2 conventional turbos and a third electric "e-booster" to help spool them up. This one is "five to 10 years" away.
-A 2.0L 4-cylinder 'Drive-E' engine coming to market on the 2016 XC90 that has a turbo- and a supercharger (but no electric fan).