The big news for the 2008 BMW 5 Series sedans lies under the hood of the six-cylinder models. For 2008, the base 528i gets a horsepower increase that makes it the most powerful entry-level 5 Series ever. With a new twin-turbo engine, 535i and 535xi Sedans and Sports Wagon are the quickest six-cylinder-powered 5 Series cars yet. The six-speed Steptronic automatic transmission has been improved as well, and buyers can choose manual or automatic for the same price in all models.
In any iteration, the 5 Series is pleasure to drive, though it's hard to say which model we'd choose. The least-expensive 528i feels delightfully light on its feet for a clean, satisfying driving without a lot of high-tech aids to get in the way. On the other hand, those high-tech systems like BMW's Active Steering or Active Roll Stabilization can quickly demonstrate their value, and there's nothing quite like the thrust developed when you slam the accelerator down in a 550i.
The 5 Series is not whisper quiet like the BMW 7 Series, so a bit more road and ambient noise finds its way into the cabin. Yet with the stereo turned up about two-tenths of the way, you won't hear any of it. And the 5 Series feels smaller on the road than its dimensions suggest. Consider its near-perfect weight balance, and a rock-solid body that's free of creaks, rattles or unpleasant vibration, and this BMW is exactly what we'd like a luxury sedan to be: smooth and comfortable regardless of the speed, nimble and reassuring when it's appropriate to travel at a good clip. The 5 Series has nearly all the bells and whistles, and almost nothing to diminish the driving experience. If you decide to pick up the pace, you'll discover handling and overall performance that's hard to match in any sedan. No matter which engine sits under the hood, there's plenty of power to get you up to speed.
The 5 Series engines were updated for 2008. They were overhauled for 2006, starting with a new inline six cylinder that is the only current production engine with a magnesium alloy engine block to reduce weight. The engines in the 2008 BMW 528i and 535i are actually the same size, 3.0 liters.
The 528i engine generates 230 horsepower and 200 pound-feet of acceleration-producing torque, or 15 more of each than the 2007 525i, thanks to improvements in tuning and control systems for 2008.
The 535i engine is considerably different. It has gasoline direct injection, the most advanced means of delivering fuel to the cylinders, and twin turbochargers that boost power to 300 horsepower and 300 pound-feet of torque, or 45 horsepower and 80 pound-feet more than the 2007 530i. That's more power from a six-cylinder than the V8-powered 5 Series cars had a few years ago.
BMW's inline six-cylinder engines remain one of the great experiences in motoring. The classic straight six delivers a balance of smoothness, torque, and response that V6 engines can't seem to match. Other luxury manufacturers have switched to V6s because they're easier to package, and they've proven easier to certify for stringent emission standards. We're glad BMW sticks with its trademark inline engines.
The 535i's twin-turbo 3.0-liter engine might be the finest yet. From a stop or a high-speed roll, the 535i delivers as much torque or more than some thirstier V8-powered sedans. Off-the-line acceleration surpasses probably 80 percent of the vehicles on the road, and top speed exceeds anything you'll get away with anywhere outside desolate Nevada desert. Power delivery in the 535i is very linear, even with the turbochargers, meaning that you'll get the same response and acceleration whether the engine is turning 2500 rpm or 5000 rpm when you step on the gas. There's virtually no turbo lag in this engine.
The 550i with its V8 engine appeals to those who put a premium on straight-line acceleration and turbine smoothness. This 4.8-liter engine delivers 360 horsepower and 360 pound-feet of torque, and its impressive power flows in the same even fashion as it does from the six-cylinders.
The 550i is a true high-performance sedan; holding its accelerator to the floor is a truly enjoyable experience. The 550i will squirt from 0-60 mph in about 5.4 seconds, which is substantially quicker than the performance from the Jaguar XK or Nissan 350Z sports cars. Top speed is electronically governed at the voluntary limit adopted by most German automakers: a mere 155 mph.
For those who don't mind a little work, we heartily recommend the six-speed manual gearbox. It's one reason to choose the 5 Series over other luxury sedans, in which manuals are increasingly few and far between. The shifter is tight and reasonably quick, and shifting is smooth, precise and easy. Particularly with the six-cylinder models, the manual transmission maximizes performance potential, as well as the driver's involvement.
The great majority will choose BMW's six-speed Steptronic automatic, and they won't give up much. The Steptronic's innards have been massaged for 2008 to increase shift speed, which improves both efficiency and acceleration. For 2008, it features a drive-by-wire electronic gear selector, meaning the shifter merely sends an electric signal to the transmission, rather than mechanically engaging the gears.
For 2008, a new Sport Automatic is available for the 535 models and 550i, which adds paddles shifters on the steering wheel and delivers even quicker, crisper shifts in manual mode. With this option, BMW's Sequential Manual Gearbox is no longer offered in the standard 5 Series. In a luxury sedan like this, we won't miss it.
The Steptronic automatic reacts to the gas pedal in fine style. Full-throttle upshifts are quick and smooth, and downshifts, in most cases, come quickly. We like to leave the automatic in Sport mode, as it responds even more quickly, shifting down instantaneously when you dip the gas pedal and allowing the engine to rev higher more often. The downside is that the automatic can feel more jarring in Sport mode. If a serene experience is preferred for the drive home, choose the Comfort setting.
When it comes to handling, we like the six-cylinder models, and particularly the 528i. Despite its horsepower deficit compared to the other models (it's no lightweight), it's spry, and light on its feet. This is a good, honest sedan in the BMW tradition, with a comfortable ride, precise steering and nice, sharp handling, and without a lot of high-tech stuff to muddle the picture.
Still, those high-tech add-ons have their appeal. BMW's optional Active Steering, for example, is more than a gimmick. Maneuvering through tight confines is a breeze, and pulling into an empty parking space is a quick swoop of the steering wheel. On a tight slalom course, a 5 Series with Active Steering is more responsive than one without it. Weaving through the cones is less work, requiring less sawing at the wheel and fewer corrections. The driver can focus more on the car's trajectory through the course, less on compensating for mistakes. Active Steering is tied into the electronic stability control. It can automatically make slight steering adjustments without driver intervention.
Another such system is BMW's Active Roll Stabilization. ARS replaces what enthusiast drivers know as conventional anti-roll or anti-sway bars with an electronically controlled, hydraulically operated system. It helps reduce body roll corners, allowing flatter cornering at higher speeds while not compromising the nice smooth ride. With Active Roll Stabilization, the 5 Series stays remarkably flat through fast, sweeping curves, with just enough body lean to remind a driver that he or she is hurtling down a public road at considerable speed. And the best thing about ASR is that it accomplishes this without the stiff springs and shocks often used in sports suspensions. When the car is traveling straight, the effect of the roll stabilization is essentially negated. This 5 Series rides firm, without a sensation of floating, but always smoothly and comfortably.
BMW Night Vision uses a thermal-imaging camera with Far Infra-Red technology that highlights sources of heat (the tailpipes on cars ahead, for example, but more importantly the cyclist or deer lurking beyond the headlights). The camera has a range of nearly 1,000 feet, and it displays a high-contrast image on the navigation screen when Night Vision is turned on. By design, the image is not highly detailed, and those high-heat people or animals are supposed to stand out more quickly. The system is intended to work like a rear-view mirror, with potential hazards standing out in a quick scan. Our time in a BMW 550i equipped with Night Vision was confined largely to an urban setting, and in this environment its value is reduced. With so much ambient light, and traffic, the camera doesn't offer much more than an alert set of eyes. Yet a drive into the dark countryside expressly to test Night Vision demonstrated the system's potential. The thermal-imaging camera picked up a truck's exhaust pipe almost as far ahead as its tiny taillights were visible. Had that exhaust been the body heat of a large animal, with no taillights to mark it, the 5 Series driver would be aware of the animal long before it's visible to the naked eye. The problem with Night Vision, beyond its high price tag, is the novelty factor. We found ourselves occasionally fixating on the screen, noticing which parts on SUVs ahead were warmest from friction, or looking at the warm bodies walking into restaurants, at the expense of peering through the windshield. We suspect that it will take some acclimation, and discipline, to get past the newness and use Night Vision as it is intended.
The optional Adaptive Xenon Headlights are excellent. They deliver bright, even light and real benefit on winding rural roads at night.
BMW's brakes are large by industry standards, and in the 2008 5 Series they are slightly larger than before. They remain one of the most impressive components in the performance package. They slow the car from high speed in sports car fashion, and they hold up under harder use than any driver is likely to dish out. Even after repeated stops that would smoke the brake pads on lesser cars, the 5's brakes show very little fade.
