I couldn't help shaking my head when I heard GM's (NYSE:GM) latest scheme to drum up sales: a card worth $500 in gas for the tanks of its money-sucking SUVs. That's supposed to revitalize sales that have declined precipitously in the face of higher energy costs? In a market where American garages are already full of SUVs?

Fat chance. And even if it does, it will do little to help GM. If you recall, heavy discounting got GM into its current mess. Recent monthly comparable sales are dropping like crazy because, unlike last year, this year's cars aren't being sold at giant discounts. This is the dangerous game where Ford (NYSE:F) and DaimlerChrysler (NYSE:DCX) do just about anything to gain worthless "market share" against each other, or against less desperate foreign competitors Honda (NYSE:HMC) and Toyota (NYSE:TM).

Let's review: When you lose money on every product you sell, selling more of it is rarely a good thing. Unless, of course, you can make money by convincing the people who buy that thing to finance it with you. Then you might squeak by -- but not necessarily. As today's walloping loss shows, GM is giving away a pretty expensive toaster every time it signs up one of these new bank accounts.

But the mere possibility that a finance-based model could be the only sustainable route for big American auto brings us to an odd realization. GM's gas gimmick might only be the second or third dumbest idea out of GM in the past few weeks.

At the top of my list is the continuing sale of the finance wing -- the profitable part of the business, mind you. The reason, if I've understood it correctly, is this: It'll get debt off the books, which might raise GM's current junk debt rating, which could then lower the costs of borrowing. It's not exactly killing the goose that lays the golden egg -- more like tossing aside the only consistent egg-provider you've got, all so that you can borrow more cheaply to run the unprofitable leftover with crummy sales and cutthroat competition.

If GM had a plan to run the company without having to borrow like its life depended on it -- because it does -- then we might have something. Until then, I'll be wondering, as I have for a long time, why anyone might want these shares.

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Seth Jayson would much rather own an American car than an American carmaker. At the time of publication, he had positions in no company mentioned. View his stock holdings and Fool profile here. Fool rules are here.