2012 BMW 528i review

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When I first heard that BMW was going to replace the 3-liter six-cylinder engine in the base-model 5-series with a 2-liter four-banger (man, that's a lot of numbers in one sentence!), my first thought was, "How's that going to work?"

Turns out, it works. In fact, it works like crazy.

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More and more automakers are finding fuel economy gains by lopping off cylinders and adding turbochargers. A turbocharger, in case you're not familiar, is basically an exhaust-driven air pump. When the engine is revved, the turbo forces more air into the cylinders than the engine would normally "inhale" on its own. More air means the fuel injectors can spray in more fuel, and when the spark plug fires you get a bigger bang and more power. It's essentially force-feeding: The turbo makes a small engine do the work of a big one by packing in big-engine volumes of fuel and producing a big-engine bang, resulting in big-engine power.

So why not just use a big engine? Ah-hah! That's where the exhaust-driven part of the turbocharger comes in. Turbos only do their thing when the driver demands power; when the car is driven gently, the turbo essentially remains dormant. The engine inhales four cylinder's worth of fuel and air, and gets four-cylinder gas mileage. A six, meanwhile, always needs six cylinder's worth of air and fuel. Pretty slick, eh?

Despite knowing the theory, I had my doubts about a four-cylinder 5-series. The 5 is a big car, after all, and even powerful turbocharged engines take time to build up steam. On paper, however, BMW appears to have all the bases covered.

The 528's 2-liter turbo four -- which looks tiny in the 528i's engine bay -- is rated for 240 horsepower, same as the 3.0 liter inline six it replaces. Torque is 260 lb-ft, up from 230 in the six, and while the six's torque peaked at 2,600 RPM, the turbo four maintains maximum torque between 1,250 and 4,800 RPM. Naturally, fuel economy is up -- EPA estimates are 23 MPG city/34 MPG highway/27 MPG combined, compared to 22/32/25 for the six. (Meanwhile, the 535i and 550i retain their respective six- and eight-cylinder engines.)

What is the 4-cylinder 5-series like to drive? Not much different than the six-cylinder car, actually. From a stop, the turbo four doesn't exactly leap off the line, but then again neither did the old six. Once on the move, the turbo engine's prodigious torque combined with a quick-witted 8-speed automatic transmission means that there's always power on tap when you need it. Select Sport mode from the 5's dial controller, which quickens both throttle and transmission response, and you may well forget that the 528i has the same size engine as a Kia Forte.

Speaking of Sport Mode, at the opposite end of the dial is the new Eco Pro setting, which relaxes the throttle response and replaces the real-time MPG gauge with a bar graph that coaches you to drive more economically. I did most of my driving in Eco Pro, and was quite pleased to see that by week's end I was averaging 26.3 MPG, pretty close to the EPA's combined figure of 27 MPG. In fact, I was averaging exactly 27 before I took a run on the About.com Top Secret Curvy Test Road, on which my rear-drive 528i tester acquitted itself nicely. Big as it is, the 5-series isn't the sharpest nor most graceful of BMWs, but it still feels properly German in the curves, and with the dial set to Sport Plus, I didn't miss the extra two cylinders at all -- in fact, I even managed a wee bit of power-on oversteer (goosing the gas and flicking the tail out).

My one big complaint about this engine is the soundtrack. BMW's sixes and V8s sound musical when revved, but the 528's 4-cylinder sounds like a Chevy Cobalt with bronchial disease. Honda, Mercedes-Benz, and even Toyota make sweet-sounding fours; with BMW's attention to driver-oriented detail, I'm surprised they let this one slip through the cracks.

Another problem: BMW has fitted the 528i with an auto-stop system that shuts the engine off at stoplights. I like the idea, but I'm lukewarm to the execution: The car shudders every time the engine shuts off and again when it restarts. General Motors has a similar system in the Buick LaCrosse eAssist, but it's so well engineered that you can barely detect when the engine stops and restarts. If GM can achieve that sort of perfection in a $30,000 Buick, surely BMW put a bit more work into the $48,000 528i.

You can turn off the Auto Stop system, but that leads to my third complaint: The car doesn't remember your Auto Stop or drive-mode selections. If you don't like Auto Stop, you have to turn it off each time you start the car. Likewise, I had to re-select Eco Pro every time I started the car -- the car kept defaulting to Comfort. Annoying.

These are relatively minor problemissues, and the 5-series is still the same excellent car that won a spot on my Best New Cars of 2011 list. It's big and roomy, plush and quiet, sufficiently comfy in Comfort mode and sufficiently sporty in Sport mode. Pricing now starts at $47,795, which is $1,850 more than last year's six-cylinder car -- ouch. The price does include 4 years or 50,000 miles' worth of free maintenance, but BMW charges extra for many luxury-car should-haves -- items such as genuine leather seats ($1,450, plus $500 more if you want 'em heated), navigation ($1,850), proximity key ($1,000) and any paint color other than black or white ($550). My test car had all of the above (except for extra-cost paint) plus a sport package, power trunk lid, and a parking-assistance system, and listed for just over $57k. That's about what I expect to pay for a big BMW, but you can option the 528i up to nearly $80,000.

The 5-series faces a formidable challenge from Audi's new-for-2012 A6. I tested the V6 version and thought it was a fantastic car, and Audi has their own 4-cylinder turbo engine on the way. The 4-cylinder A6 combines Audi's proven 211 hp 2-liter turbocharged engine with a continuously-variable automatic transmission (CVT) and front-wheel-drive; the 528i's more powerful engine, 8-speed automatic transmission and choice of rear- or all-wheel-drive give it bragging rights, but the Audi is priced at $42,575 complete with standard leather seats. For five grand, I'm not bothered if someone else brags.

The A6 may be the better buy, but I'm still a fan of the 528i. I'm impressed that BMW has given us a fuel economy improvement of around 8% while improving performance and without altering the basic character of the car. If this is the future of fuel economy, bring it on! -- Aaron Gold

• Better fuel economy with no trade-off in power or driving pleasure
• Roomy back seat
• Quiet, comfortable ride

What I didn't like about the BMW 528i:

• Engine note doesn't fit the car's character
• Unrefined auto-stop system

Other cars you should consider:

• Audi A6
• Lexus GS 450h
• Mercedes-Benz E320 BlueTec

2012 BMW 528i details and specs:

• Price range (528i, including options): $47,795 - $78,495
• Powertrain: 2.0 liter turbocharged 4-cylinder/240 hp, 8-speed automatic, rear- or all-wheel-drive
• Where built? Germany
• EPA fuel economy estimates: 23 MPG city/34 MPG highway
• Standard safety equipment: Front airbags, front seat-mounted side airbags, two-row side curtain airbags, antilock brakes, electronic stability control
• Warranty: 4 years/50,000 miles bumper-to-bumper, 12 years/unlimited mileage outer body rust-through
• Roadside assistance/free maintenance: 4 years/unlimited mileage roadside assistance, 4 years/50,000 miles free maintenance

Disclosure: The vehicle for this review was provided by BMW. For more information, please see our Ethics Policy.