The engine will deliver 303 hp, up 23 hp from the current version. It will be available on most trim levels at no extra cost from the LaCrosse's standard 2.4-liter, four-cylinder engine with GM's eAssist mild hybrid stop-start system.
Despite the added power, the new engine will deliver the same fuel economy as the current V-6: 17 mpg city/27 highway.
GM is using "lighter-weight components and enhancements to improve the engine's performance, efficiency and durability," Tom Sutter, global V-6 engineer, said in a statement.
The engine is made of a lighter-weight aluminum alloy. A new cylinder-head design has larger intake valves and longer-duration intake camshafts. Holding open the larger valves longer pulls more air into the combustion chamber, producing more power.
The 2012 LaCrosse will be the first GM vehicle to get eAssist, which combines a lithium ion battery and an electric motor-generator that enables regenerative braking.
The powertrain will generate 182 hp and get 25 mpg city/37 highway, GM estimates, up from 19 mpg city/30 highway on the 2011 model.
LaCrosse sales are down 7 percent this year, to 23,362 units, through May.
