As an enthuaists of GM products since I was a little one, I hate to seem them in the position they are in, and I wish I could put my two cents into the operation of their company.
GM's biggest problem I think is the fact that they keep trying to sell a full product line to each nameplate, instead of giving each nameplate it's own niche and character. Prior to the 1970's, each GM nameplate had it's own character, and many even designed their own engines and other mechanicals. GM's biggest problem is that their divisions seem to me to be a "me too" type of thing, selling vehicles just because someone else does, and not because they are innovative or popular. Here's my outline to the way GM should tune their product line:
Chevrolet: The only division that should feature a full product line of vehicles from pickups, SUV's, Vans, sedans, coupes, sports cars, etc. These vehicles should feature traditional American characteristics in vehicles, like rear drive. Styling should be attractive, but relatively subdued. Prices should be affordable, with a wide variety of optional equipment and features avaliable.
Saturn: Compact and mid-size vehicles in both coupes and sedans, sports cars, and car based SUV's. Saturn vehicles should be more Asian like as they have been in the past with features like front-wheel drive & MacPherson strut suspensions.
Pontiac: Full-size, mid-size, and compact sedans and coupes, and sports cars, pony cars and other "muscle" cars. Traditionally known as the performance division of Pontiac. It has been caught up in making gawdily styled vehicles that lack the critical performance factor. Pontiacs should styled to be sporty, but not too tacky. Pontiacs DO need to have powerful engines, tight suspensions, manual transmissions, and other performance goodies. Large cars need to be rear drive, and V8 based, playing up the classic Musclecar theme that made Pontiac famous. Smaller sedans and coupes can be front-drive to take a piece of the "rice rocket" market, while sports cars can be mid-engined, or front-engined /rear drive to be similar to traditional sports cars from Europe. Pontiac does NOT need to be selling car and truck based SUV's, Minivans, wagons, or any other type of utilitarian type vehicle that can water down the performance image. (Astec anyone?)
Oldsmobile. Yes, I know GM doesn't sell under the Oldsmobile nameplate, but why not? It's got a great heritage and history. This division needs to be selling full-size and mid-sized sedans and coupes, along with station wagons, minivans, and car based SUV's. Oldsmobile used to be GM's technology devision, and the place where GM would showcase their latest designs before they trickled down into other divisions. The trick was GM put this technology and modern styling into the utilitarian type vehicles that moved our families and commuters everday making driving more comfortable and convenient. Oldsmobile should NOT be selling sports cars, compact vehicles that aren't all that utilitarian. Truck based SUV's and other vehicles water down the high-tech image of the company too, as most people see trucks as not very technologically advanced.
Buick: Full sized sedans, coupes, wagons, minivans, and maybe even truck based SUV's. Buick traditionally has an "old man" image, but it could easily move in on Mercedes Benz's luxury sedan territory with a refinement in suspension technology, and an increase in engine refinement and performance. Ripping off Cadillac's Northstar engine is a step towards this, but Mercedes needs to be using full-frame rear-drive platforms with fully independent suspensions just like the rest of the luxury car market does like M-B, Lexus, infiniti, etc.
Cadillac: One of the only divisions of GM that has actually hit the market nail right on the head! Cadillac should have a wide range of high-end vehicles avaliable like cars of all sizes, truck based SUV's, and even sports cars. They are actually building all of these, and are selling them reasonably good. The only issue with Cadillac is that it should not be installing un-refined Chevy engines in their SUV's, but should design their own version of the Northstar that would power the SUV's...like it did with the XLR sports car.
GMC-Truck: Selling nothing but trucks, and truck based vehicles! No front-drive minivans or other car based vehicles
Here's how the vehicle platforms would square up:
Small sports car: Chevy, Pontiac, Saturn
Ponycar musclecar: Chevy, Pontiac
Larger sports car: Cadillac, Chevrolet, maybe Pontiac
front-drive compact sedan/coupe: Chevrolet, Pontiac, Saturn
rear-drive compact sedan/coupe: Cadillac, Buick maybe
Front drive mid-size: Chevy, Saturn
Rear-drive mid-size: Olds, buick, Cadillac
Full-size rear-drive: Chevy, Pontiac, Olds
premium rear-drive platform: Cadillac, Buick
car-based minivan: Olds, Buick, Chevrolet
Car based SUV's: chevy, olds, buick, Saturn
Truck Based minivan: Chevy, GMC
Truck Based SUV's: Chevrolet, GMC, Buick maybe, Cadillac
Each division should be able to develop it's own unique engine design. It can be shared among a few similar divisions, but not all 5. For instance, the Chevy "Small-block" V8's and V6's can be shared with Pontiac, Pontiac could also develop a high performance "rice rocket" motor that could also be shared with Saturn
As you can see, there's no "6 flavors" like they are currently building, and most platforms are only built among 3 product nameplates. Yes, you probably see some correlations to currently offered GM products, like the new Pontiac Solstice & Saturn Sky, or the unique to Cadillac CTS rear-drive mid sized platform. I included these because they seem to be the places where GM is doing it right...GM would have a heckuva time trying to sell the hot CTS if they also sold it as a Chevy! Why would someone want to buy an over-priced Chevy...that's what they gotta think about, along with other products that weaken the nameplate's image!