The battle of big American quasi-luxury sedans is heating up as the 2010 Buick LaCrosse nears production. Although this is our best set of spy photos yet, it's still rather silly as the Buick Invicta concept essentially previewed what's hiding under the camo here. As you can see, Buick is taking dead aim at the Lincoln MKS for the coveted role of "car for sexy grandfathers" title. Spy report after the jump.

We caught a convoy of 2010 Buick Lacrosse prototypes running on public roads—this time with drastically reduced camouflage. Prior Lacrosse test vehicles had always been clad under oppressive covers, but now we can see all but the finest details on Buick's new sedan. The prototypes captured here definitely show a resemblance Buick's Invicta concept car shown in China earlier this year.

Two distinct prototypes were identified in the group: one with no visible exhaust tips and a clean rear bumper, the other with sporty dual exhaust tips cut into the bumper and larger, more aggressive wheels.

We also managed a revealing interior shot, showing the impressive feeling of craftsmanship that will be applied to the Lacrosse's passenger compartment. It looks as if Buick stylists have learned a lesson, or two, from the Cadillac CTS' interior design.

The test group had an interesting mix of comparison vehicles along for the ride, covering a wide range of market segments. Running alongside the Lacrosse prototypes were a Mercedes E-class, a Lincoln MKS, and a Volkswagen Passat.

Send an email to the author of this post at marnold@hfmus.com.