It looks like the aim for the new BMW 5-Series is bigger and lighter. The new sedan is expected in 2010 (possibly as a 2011 model) and will share a platform with the the 6 and 7-Series. Because it’s now sharing underpinnings with its big brother, the next 5-Series will gain at least a few inches in length.

Even with this additional room, the sports sedan is expected to be lighter than the current car. BMW plans use aluminum on for the roof, fenders and other large body panels. Also expected on the new 5-series will be adaptive damping, integral steering, side-view cameras, and a night vision aid for recognizing pedestrians in the dark

Another place BMW will find a weight savings will be with the engines. As reported last month, the top of the line M5 will drop the V10 in favor of a lighter twin-turbo V8. Turbocharging will also likely help lesser models as well. It’s rumored that engine choices may include a 3.0-liter twin-turbo straight six for the 540i; a 4.4-liter twin-turbo V8 for the 550i; and even a twin-turbo diesel model for the U.S.

If this is correct BMW has finally abandoned its car naming structure, which used to give the series number followed by the engine displacement. For example the previous generation (E39) BMW 525 was a 5-Series with a 2.5-liter inline six cylinder engine, but the current 525 uses a 3.0-liter inline six. This is what made BMW car so cool. They were noting more than precision instruments, and so they were named that way.

If the names can go what’s next a BMW minivan? BMW don’t abandon what makes you cool.