First drive: BMW ActiveHybrid3 takes powerful rather than economical approach to hybrids

This hybrid is fast! When BMW engineers set out to design a hybrid system for the iconic 3 Series sports sedan, they wanted to break the green-car mold. And break it they did.

The ActiveHybrid3 packs a ton of technology into one small car: A hybrid system, lithium-ion battery, variable-valve timing, twin turbos, and an eight-speed automatic transmission. Unlike many hybrids, the ActiveHybrid 3 doesn't lose any trunk space to the battery, compared with any other 3 Series models. And like virtually all BMWs, it has no spare tire, but comes with run-flats.

Using the same guts as in the 5 Series ActiveHybrid, the 3 Series version uses a 55-hp electric motor sandwiched between the twin-turbo six-cylinder engine from the 335i. It's a full hybrid system, meaning the electric motor can power the car without the gas engine running. In theory, this can happen at speeds up to 60 mph, but in our driving around hilly rural New York State, we found the car couldn't accelerate to those speeds without the gas engine, though it could putter around easily in electric mode at city speeds once we slowed down. The engine shuts off and restarts seamlessly at stops, though on the hot day we drove it, we found it has to run the engine for the air-conditioner to keep up with mid-80's temperatures.

Once the gas engine kicks in, hold on! The engine cranks out 300 hp, which combines with the electric motor to produce 335 hp--more horses than any current 3 Series save the mighty, V8-powered M3. Despite all that power, the EPA estimates the ActiveHybrid 3 averages 28 mpg, the same as we got from the much more pedestrian four-cylinder powered 328i we tested last year. Clearly, this isn't a pure efficiency play. It's a technology showcase wrapped in green. Or, if you will, the balance of power and efficiency.

The problem with the system is that the discrepancy between the power of the electric motor and the gas engine is so vast that it can be hard to manage. But in a rolling start, if you try to accelerate a little harder than the electric motor can deliver, the gas engine starts (smoothly), then slingshots you forward until you back off the throttle. It makes it hard to drive smoothly. It's not as jerky as in our experience with the Infiniti M35h, but is as dramatic.

The other problem with the ActiveHybrid3 is the price. It starts around $50,000, and that's without seat heaters. From there the price can climb to over $60,000.

In contrast, the very good 328i we tested cost almost $10,000 less. For buyer's seeking efficiency, BMW is also introducing a new diesel version of the 3 Series, the 328d, which should get even better mileage and still has tons of torque.

It makes us wonder whether more buyers might choose a 3 Series hybrid if it were powered by one of BMW's excellent four-cylinder engines, cost less, be easier to drive, and returned even better fuel economy.