OK, what about customers extremely loyal to the brand because of its stellar reliability record? Why not give them a large SUV? That's good reasoning, and one that I'm sure played an important part in GM's decision to build the Rainier.

The Rainier is the sport utility that Pontiac-Buick dealers have been longing for. (Photo: Shawn Pisio, Canadian Auto Press)

But even more important are GM dealers that sell only Buick and Pontiac brands, none of which offered an SUV prior to the Rainier - crossovers such as the Rendezvous and Aztek not included. I don't know how many of GM's dealers are in such a predicament, as all I've been able to check out in my town also offer GMCs. But if Pontiac-Buick dealers do exist no doubt they've been screaming for an SUV for years, with others that are in the process of losing their Oldsmobile franchises demanding a Bravada replacement to fill the void. Jackpot! If there ever was a reason for the Rainier's existence, this is it.

GM engineered the Rainier to not only look different than its Envoy counterpart, from the front at least, but offer different driving dynamics too. (Photo: Shawn Pisio, Canadian Auto Press)

So now that I've speculated on the reason for Buick's version of the Envoy, what's it like to drive? It would be easy to just end it hear with a "go to GMC Envoy" tagline but that wouldn't be fair. After all, GM engineered the Rainier to not only look different than its Envoy counterpart, from the front at least, but offer different driving dynamics too. Its ride seems softer and smoother, with the resultant compromise being squishier handling both on and off the road, despite its Bilstein shocks, 17-inch alloy wheels encircled with P245/65R17 front and P255/60R17 rear all-season Michelin tires - base RWD models (only in U.S.) receive P245/65R17 tires at all four corners. For me this isn't necessarily a positive step forward, but I can appreciate there are many that would take a comfortable ride over road-holding. The suspension system is independent all-round, with a sophisticated 5-link system in the rear, optimized by an even more sophisticated rear air suspension. The big difference between the Rainier and Envoy is that the "air springs" are standard (a $510 upgrade on Envoy) replacing the usual coils found out back. They do a good job reducing road noise, as well as leveling off the rear end when loaded with cargo. I didn't try towing a trailer but can also imagine the benefits under load.