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 de