Here's a video from November last:
http://www.youtube.com/watch?v=jeOsjLw711s (embedding disabled by request)
There are two cars, the first with the weird wheels looks to be a manual, and the one with black wheels appears to be an auto of some kind. They sound subtly different, too; sort of a cross between an
N55 (twin-scroll single-turbo) and an
N54 (twin-turbo).
Maybe that sound points to tri-turbo, especially if they plan on running "massive" boost to massage ~470 bhp from the existing 3-litre units.
Similarly, a triple-scroll single-turbo could be fun, I don't think it's ever got past being experimental. I can imagine that's something for the M people (ha) to get their teeth into, but the returns over a twin scroll in terms of response are probably minimal, and the plumbing and / or firing order may need serious attention (actually, that would apply more to triple, parallel turbos, which are probably pointless).
I suspect that for moderately high boost (in production car terms) they would want to go with a twin-turbo setup (i.e. two separate turbo-compressors) for better flexibility over the single twin-scroll, and less weight and complexity vs. the
tri-turbo as it's configured on the N57 Diesel. That leaves open the idea of using one twin-scroll turbine, and one mono-scroll turbine, like on those
patents, with a similar (to the tri-turbo system) medium-to-high-engine-speed switch-over to eke out maximum boost at maximum volume throughput (that is, ignoring the third, larger, "sequential", low-pressure unit, and focusing on the behaviour of the two, smaller, "semi-parallel" ones on the Diesel.) That could also explain the sound in the above video, to a lesser extent.
As for "electronic turbo", are they thinking of (electric)
turbo compounding? Keith Duckworth was after that eventually for Ford's "TEC" turbo F1 engine (Cosworth GBA) introduced in ~1986, but nothing came of it because of regulation changes for '88. There's also room for turbo compounding in the 2014 F1 regs, to complement the existing KERS.
I've read that the returns are small (~5% in fuel economy, < 10% in peak power output), and they'd probably stick it on a Diesel first because that's been done already in goods / freight vehicles (lower exhaust temperature, smaller operating range). But BMWs are, in relative terms, still big, heavy cars, and cruising at Autobahn speeds will always need so much power... perhaps not in an M car just yet, though, eh?
