This LaCrosse is the 3rd Buick I've owned, a '82 Riviera and an '89 Regal previously. They were both excellent performers giving me almost 100,000 miles each of trouble free driving. The LaCrosse has the comfort of the Riv and the economy of the Regal with plenty of power. When I step on it to pass, there is no hesitation.
I would have to say the 3.6 engine, gives performance with economy.