Written by Marc Lachapelle

BMW is giving its 7-Series flagship sedans a styling refresh and wide-ranging technical and mechanical revamp for the 2013 model year. The most visible changes are not so obvious. The signature BME twin-kidney grille now has nine vertical slats instead of the current model’s full dozen, and the chrome moldings that surround both are thicker.

Right below, the air intake that runs the full width of the grille is now split three ways, and a thin chrome bar streaks across each outer section. The fascia is unchanged in the M Sport package, though. New LED headlights are standard on the V12-powered 760Li flagship and optional on the 740i/Li and 750i/Li, which come standard with adaptive xenon beams. Squint and you will also notice a second chrome strip that links reflectors in the taillights.

Changes are numerous and significant under the various hoods. The 740i and extended-wheelbase 740Li get the newest (N55) version of BMW’s vaunted 3.0-liter inline 6-cylinder engine, now with a twin-scroll turbocharger, direct injection, Valvetronic throttling and infinitely variable camshafts. It now produces 315 horsepower and 330 lb-ft of torque and consumes 20 percent less fuel according to European standards. Both 740 versions are now also available with BMW’s all-wheel-drive system. More power and torque for the 750i/Li models’ 4.4-liter V8 engine, too, thanks to similar upgrades. The output swells to 445 horsepower and 480 lb-ft of torque for a claimed zero-to-60 sprint in 4.7 seconds and yet a 25 improvement in fuel usage.

At the heart of these gains is a new 8-speed automatic gearbox that is shared with the second-generation ActiveHybrid 7 model in a specially adapted version. Its hybrid powertrain is now built around a turbocharged 3.0-liter inline 6 instead of a V8 and has a total combined output of 349 horsepower with 367 lb-ft of torque. It reportedly zips to 60 mph, sips 14 percent less fuel than the thriftier new 740i and can be driven up to 2.5 miles on electric power alone at 37 mph.

Engineers in Munich have also made myriad changes to suspension components to improve the 7’s ride and several more to reduce noise levels. On the other hand, a new optional Bang & Olufsen audio system is tasked with generating highest-fidelity sound inside, a new-generation navigation system with 3-D elements should keep you on course, and BMW is claiming further improvements to its once-reviled iDrive interface. "Version 4.2," as a BMW insider quipped, is said to be quicker. Some of the other new features include slimmer front seats and a trunk you open by swinging a foot under the rear bumper.

The new 7-Series will arrive later this summer and the ActiveHybrid 7 in early fall. Price has yet to be announced.