The Case of the Unlikely Loudspeaker

I was mystified, confused, and perplexed. The low-slung vehicle cruising in the lane beside me sure looked the business, and sounded the business too. As it briskly accelerated away from me, its low throaty roar was decidedly delicious. Something was amiss. Very amiss.

The BMW i8 is an innovative vehicle. One look at its futuristic styling is enough to convince you of that. It is built with a carbon-fiber-reinforced plastic body on an aluminum chassis complete with flying buttresses, and if the styling isn't aggressive enough for you, consider that the doors swing up in a very attention-getting "butterfly style."

It also uses a plug-in hybrid, all-wheel power train. The front wheels are driven full-time by two electric motors powered by a 11.6-kilowatt-hour battery that enables it to go about 18 miles on electric power alone. The rear wheels are powered under hard acceleration with a turbocharged 1.5-liter gas engine; otherwise, the gas engine acts as a generator to keep the batteries charged. The combined output is a respectable 369 hp and the i8 runs 0 to 60 mph in about 4.2 seconds for the coupe and 4.4 seconds for the recently introduced roadster.

But let's go back to that gas engine for a second. It is a 3-cylinder engine and in fact is the same engine (but tweeked) that you'll find in a Mini Cooper. If you've listened to a Mini lately, or any inline 3-cylinder engine, you might begin to understand my confusion. The i8 sounds pretty darn good under acceleration, but any 3-cylinder engine does not....

Inside the i8, as you might expect, it uses Active Sound Design to provide occupants with a nice engine note. ASD certainly isn't anything new and many cars (possibly including yours) use ASD in various ways and with different degrees of artificiality, ranging from acoustic tubes that connect the engine compartment to the interior, to fully synthesized engine sounds played over the stereo. My thoughts on ASD are complex, and I promise that I'll write about that soon enough. But the i8 also sounds darn good outside the car. How is that possible with a hybrid drive train?

Well, you probably guessed that it has something to do with tailpipes. The vehicle has two tailpipes. The right-side tailpipe is indeed an exhaust pipe from the 3-cylinder engine. Inside the left-side tailpipe is a friggin' loudspeaker that plays virile exhaust sounds so that passersby can appreciate the aural power and beauty of your i8.

Don't get me wrong. The i8 is a wonderful vehicle. I would love to have one. And it is a simple reality that a performance car must sound as good as it looks. Visceral sounding, ideally. Hence the loudspeaker in the tailpipe. Is that cheating? Maybe. Is it wrong? I'm not sure. In any event, this case is closed.

PS: That isn't the only external loudspeaker on the i8. There is also a loudspeaker on the front of the car; when in electric mode, it sounds an alert if it detects a pedestrian in its path.

PPS: None of my vehicles need either of those loudspeakers.