Detroit — Thirty five years ago, Congress dictated to automakers that vehicles get 40 percent better fuel economy (28 mpg cars, 23 mpg trucks) with results that were disastrous for Detroit. The forced downsizing of cars gutted profit margins, drained off jobs, and ceded market share to upstart, small-vehicle-oriented foreign automakers.

Today, Washington is back for a second bite at the apple, again dictating 40 percent mpg increases and forcing automakers to build small cars customers don’t want. But automakers have learned their lesson. This time, as Holman Jenkins pointed out in a superb column in the last week’s Wall Street Journal, Big Auto is making sure taxpayers help shoulder their burden.

Under the old business model, Detroit simply dumped cars on the market or into rental fleets at a loss in order to hit their fleet average mpg target. But such waste is no longer tenable in a U.S. market where Toyota, GM, Honda, and Ford go toe-to-toe for market share.

Cue public subsidies. Detroit has used its lobbying muscle to wring $25 billion out of Washington to pay for electric- and hybrid-car development. A further $2,500-$7,500 will underwrite the purchase of each alternative fuel car.

Big Auto welfare is now an essential piece of the U.S. auto business model. That welfare will go to foreign manufactures, as well — in the form of sales subsidies and loans for retooling factories. Nissan, for example, is receiving hundred of millions in tax dollars to convert its Tennessee plant to build hybrids (to add salt to the wound, Nissan is half-owned by the French).

The sausage-making gets more cynical since Washington’s new 35 mpg mandate for all vehicles is at odds with what Americans actually buy.

Indeed, the average fuel economy for cars and trucks sold today is just 21.1 mpg, well short of the mandated 25 mpg average. Automakers make up the difference with alternative-fuel credit loopholes. How will carmakers make 35 mpg by 2015? Bigger loopholes. Industry experts say the Byzantine fuel rules contain credits galore for plug-in hybrids like the Chevy Volt which is predicted to get an EPA mpg rating of 100 mpg.

Which is why the sound you don’t hear at this year’s Detroit Auto Show is Big Auto whining about government green mandates. That’s because you are paying the bill, dear taxpayer.