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Motor Trend fell deeply, rhapsodically in love with its long-term diesel stormer, the 2009 BMW 335d. That 3.0-liter/265-hp/425-lb-ft I-6 hotrod oil-burner was priced near the top of the range and delivered amazing performance (5.8 seconds to 60 mph), while returning quite respectable fuel economy (EPA ratings of 23 mpg city/36 highway, and an observed average of 29.4 mpg over 30,733 miles). The 335d accomplished its mission of completely rehabbing any lingering image problems the technology might have suffered from the slightly wheezy 524td. Today, BMW believes diesel buyers expect highway ratings in the 40s -- as delivered by our current diesel long-termer, the roomy VW Passat TDI. So the next 3 Series diesel, the 2014 328d (specs/photos), will get the latest 2.0-liter TwinPower turbodiesel I-4, codename N47.
Output drops to 180 hp and 280 lb-ft or torque (at 1750 rpm), and 0-60-mph times will stretch to about 7 seconds, but we're promised a 4 in highway fuel economy. Final EPA figures are expected any day, but BMW expects a 20 percent improvement over the 2.0-liter TwinPower turbo gas version, with which this engine shares some 40 percent of its parts, including the aluminum block. If that holds true, we'll see 28 mpg city/40 mpg highway in the automatic sedan. With a 16-gallon fuel tank, that adds up to over 640 miles of bladder-busting highway range.
When it goes on sale later this summer (production starts in July), the 328d will be offered in both sedan and wagon bodystyles with all options available on the gasoline models (including xDrive all-wheel-drive), with one exception -- no manual transmission. The take-rate was just deemed too small, and it would have presented the conundrum: Bring the super-wide-ratio Euro box that would blunt performance relative to the eight-speed automatic, or bring the performance-oriented ratios that might kill that 40-mpg number?
To meet U.S. NOx emissions regulations, the engine uses a selective-catalytic-reduction (urea) fluid. The onboard tank is not expected to require refilling between oil-change intervals (typically 6000-10,000 miles), unless it's being operated a lot in very cold weather or at higher altitudes.
On the eve of the New York auto show, BMW offered brief test drives around its New Jersey headquarters, which revealed the new engine's more earnest earth-hugging mission. This 328d sedan seems to strike a better balance between performance and fuel economy, and as such it comes off as better optimized for drivers inclined toward obsessively Tweeting their fuel economy. Nevertheless, floor the throttle in Sport+ mode and it surfs the waves of 280-lb-ft torque, merging smartly with freeway traffic or easily jumping ahead of a line of dawdlers for the right-hand-turn lane when necessary. Yet, it feels more at home in the EcoPro transmission setting. Leave it there, and you'll never feel either edge of the torque plateau as the car wafts from ratio to ratio seamlessly. The four-cylinder's firing pulses are enough farther apart than the six's that it sounds a bit more diesel-y too, but never objectionably so.
Pricing has not been finalized yet, but we're told to expect it to fall between that of the 328i and 335i, probably closer to the former (unlike the highway economy, here they're targeting sub-40). The 335d only accounted for about 8-10 percent of 3 Series sales in its day, but given the greater affordability, expanded model availability, and the addition of xDrive, expect the 328d's sales mix to approach that of the X5 diesel, which currently accounts for 20 percent of sales. Will we love it a third less than we did its six-cylinder ancestor? Doubtful, but there's only one way to find out: Deliver one 328d xDrive wagon to Motor Trend headquarters for 12 months.
Sampling BMW's Turbo Three-Banger
BMW reckons it's just about devised the ideal cylinder: bore of about 84-85mm and stroke in the 88-90mm range for a displacement of about 500cc, Valvetronic variable timing and lift, direct fuel injection, and a turbocharger. Making the cylinders any smaller makes friction and the parts count become unattractive; making them larger makes the noise and vibration of the rotating mass become unpleasant. Each such idealized cylinder can produce roughly 40-75 hp/45-60 lb-ft on gasoline and 25-60 hp/55-80 lb-ft burning diesel. How big is your car and how fast do you want to go? Depending on your answer, you'll soon be able to string together three, four, or six of these ideal cylinders. Yes, starting next year, BMW will saw its venerable 3.0-liter I-6 turbo in half and sell both ends in its smallest home-market 1 Series cars and the plug-in hybrid i8 model on our shores, with new Mini and front-drive BMW 1 Series models getting it later on. The claimed fuel economy benefit: 5-15 percent relative to an I-4 turbo sized and tuned for equivalent output.
This high degree of modularity greatly improves manufacturing flexibility, parts, and machining commonality -- and even overall quality (gas and diesel versions can share a block and many other internal parts). An I-3's exhaust pulses are far enough apart that a less-costly single-scroll turbo can deliver the same load responsiveness as an I-4's twin-scroll. (If you were wondering, Continental makes the I-3's turbo; it produces just over 20 psi peak boost in the version we're sampling.) On the downside, an even-firing I-3 does not enjoy an I-6's inherent balance. There is a natural front-to-back vertical rocking couple that BMW counteracts with a single balance shaft spinning at twice crankshaft speed, located below the block. A small sideways rocking couple induced by the balance shaft will remain, but it's not deemed noticeable enough to warrant the cost and parasitic loss of a second counter-rotating shaft.
This new family of gas and diesel I-3s will come in a range of available outputs. BMW invited us to drive an early development prototype of one of the higher-performing gasoline versions, which is good for 177 hp and 200 lb-ft and was installed in a Euro-market 1 Series hatchback. The engineers still have a lot of work to do on the noise/vibration/harshness front.
Upon start-up, it sounds a bit like a diesel, with clatter and injector noise clearly evident. BMW claims that the predominant sound frequencies produced by the I-3 throughout the rpm range overlap the I-6's, registering higher than the four's. Okay, if they say so, but the bangs are enough farther apart that it will never confuse anyone for being a six. That said, the raspy rap was decidedly sporty, except for a sour moaning note around 2000 rpm -- especially when upshifting at a speed that sends the engine back down through that speed when operating in the EcoPro mode. Sport or Sport+ speed up the shifts and elevate the shift points enough to eliminate that effect (which will surely be addressed prior to production). Beyond that, the car accelerated like any other eight-speed automatic BMW carrying about 15 lb/hp -- probably in the low 6s to 60 mph.
The ultra-sporting i8 plug-in hybrid halo car arriving here next year will get a special 220-hp version of the engine, using a larger turbocharger optimized for high-end power at the expense of low-end torque, which will be supplied by the electric motor assisting the three-cylinder. Expect WAY better performance from that car, than from a 1 Series with no E-assist.
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E36ma max.moment przy 3950obr/min E46 przy 3500obr.min
