Review by Jacob Black, photos courtesy of GM.
The flagship Buick has a big upgrade for 2017. An all-new chassis and engine plus twin-clutch AWD system and eight-speed automatic are at the heart of the new LaCrosse. Buick told us they had four focus areas to improve: performance, ride and handling, quietness, and safety; though it was obvious that fuel economy was also of significant concern.
The all-new 3.6L V6 has also been designed from the ground up to reduce noise, vibration, and harshness while also improving fuel-economy. It is, GM says, the first engine from the group which was developed with automatic stop-start technology from the very beginning. This should translate into smoother restarts. To achieve this goal the V6 has continuously variable valve timing courtesy of a geared drive on the camshaft. This allows the valves to be set to the optimum position for ignition during auto stop-start events, and then fall back into phase when the engine is running. Even the engine mounts were designed to facilitate smooth stop-starts.
High-pressure direct fuel injection delivers gains in power and economy by allowing more precise fuel metering. Despite the all new engine, power remains almost identical to the outgoing model with 305 hp available at 6,800 rpm and 268 lb-ft at 5,200. Fuel economy is yet to be determined but is promised to be greater with help from the all-new eight-speed auto.
Final drive output is via the twin-clutch AWD system which operates in front-wheel drive most of the time. When needed, up to 90 percent of torque can be sent to the rear wheels, where the twin clutch unit will split torque as required left and right.
Further improving fuel economy is substantial weight reduction of 131 kg. Of which 68 kg comes from the structure and materials, 21 kg from the chassis itself, 16 kg from the doors, hood and bootlid, 15 kg from a reduction in acoustic barrier material and 11 kg from the seats.
The power-to-weight ratio has been improved by just under seven percent as a result of these changes which were aided by a Lacrosse that is both smaller and larger than its predecessor (but mostly larger).
The Lacrosse is 40 mm lower and 15 mm longer, while the wheelbase has been pushed out by 60 mm reducing the front overhang substantially – this should provide better balance and better stability with less understeer in particular. Track has also been widened by 33 mm up front and 28 mm out back while width is up only 10 mm, shrinking the body around the footprint on the road.