BMW’s 3 Series gets a diesel powertrain and a number of detailed midlife changes in an attempt to increase its visual boldness, provide it with the latest in entertainment and communication technology, improve its environmental credentials and further enhance its reputation as being the most dynamically adept car in the toughly fought junior-luxury-car class.

The new sedan and wagon models, due to go on sale across North America in October following the 3 Series’ world premiere at the Paris motor show, are distinguished from today’s 3 Series by fresh front and rear styling that picks up on the themes established on BMW’s recently unveiled fifth-generation 7 Series. The common styling is seen as proof that the German carmaker has abandoned plans to give each model a distinctive appearance and is instead getting back to a more stylistically harmonized lineup.

Up front, the facelifted 3 Series receives a series of styling changes that BMW design boss Adrian van Hooydonk says are aimed at emphasizing its width, including a heavily profiled bumper, newly contoured hood and reworked headlamps with altered graphics.

Farther back are new exterior mirror housings and changes to the design of the doorsills. At the rear, the BMW design team has provided the 3 Series with altered taillights. The fender taillight sections retain the same shape, but are joined by a newly developed section on the trunk lid of the sedan. At the same time, the taillights have been given redesigned lenses and more striking graphics. Further enhancing the widened look at the rear is reworked bumper and rear track that on upper-end models has been extended by nearly an inch.

BMW has also brought detailed improvements to the interior of the 3 Series, including new trim combinations, a revised armrest for the driver’s door that makes the electric window controls more accessible and an updated iDrive controller that gets four selection buttons in a move aimed at reducing the complexity of its operation. The iDrive controller is also linked to a new high-resolution, 8.8-inch color monitor. Among the long list of options is an 80-gigabyte hard disc used to store satellite navigation software and MP3 music files.

Powertrains include two carryovers: the 328i with a 3.0-liter, 230-hp inline-six and the 335i with a 3.0-liter, twin-turbocharged, 300-hp inline-six.

New to the lineup, arriving in showrooms in November, is the 335d, with a 3.0-liter twin-turbo, 265-hp, inline-six diesel, which uses a urea-injection system to meet U.S. emissions standards. The diesel will be offered only in the sedan.

Transmissions include a standard six-speed manual and an optional six-speed automatic. The diesel comes with the automatic as its only transmission.