If you buy one of the new General Motors C-body cars - Cadillac Fleetwood or DeVille, Oldsmobile 98, or Buick Electra - as well as a few others cars for 1985 , you'll get a gasoline tank unlike any other ever made in the United States.
The steel for the C-body tanks has the traditional anticorrosion coating. But on top of the inside surface is a new aluminum-rich coating and on the outside, an extra coat of zinc-rich paint. The added cost is about $2 a car - a considerable expense for cost-conscious automakers.
The zinc-rich paint on the outside is understandable. It's there to defeat road salt. The aluminum-rich coating inside the gas tank protects against an altogether different sort of corrosive: methanol.
''Those are legitimate 10-year tanks,'' a GM engineer says. ''There's a lot of bootleg methanol coming in, and this will end problems with it.''
Methanol is a form of alcohol made from wood, coal, or natural gas. It is a lot cheaper than gasoline, perhaps half the price for the refiner.
Methanol, however, is difficult to handle. It attracts water and is corrosive to some materials. In gasoline, it can also cause drivability problems. When combined with corrosion inhibitors and other alcohols that are called ''cosolvents,'' however, methanol's problems are minimized.
Recently corporate warfare has been waged by some petroleum companies against others, with the auto companies weighing in as well. Such fighting is likely to continue, because it's rooted in the relative financial advantages of methanol for various petroleum companies.
Atlantic Richfield introduced its proprietary methanol in Pennsylvania and some parts of New York State last year at its Arco gas stations. The company took some real lumps in the marketplace after a television station ''exposed'' the fact that the company was using potentially corrosive methanol without saying so.
The company has a lot of natural gas in Alaska, so it would be highly advantageous for the company to make it into methanol and use it as a gasoline extender.
The Lundberg Letter, a weekly oil-industry newsletter, says the incentive to use methanol in gasoline is great, especially for Arco. The company has done a substantial amount of work on methanol over the past 15 years to make it perform well in automobiles. It has a proprietary cosolvent, Oxinol, which it sells for use with the alcohol. Arco is the world's leading producer of this kind of cosolvent.
After the ''exposure'' in Pennsylvania, four major competitors of Arco came out emphatically against it. Amoco, Marathon, Mobil, and Shell all took public positions against using methanol in gasoline.
Then the auto companies, particularly Chrysler, came out against using it. Chrysler obviously has the most at risk, because it warrants its engines and drive trains longer than the other carmakers.
General Motors took a less-severe position than Chrysler, saying it ''recognizes the favorable aspects of pure methanol as a future alternative'' to gasoline. Ford, in fact, has a small experimental fleet in California running on pure methanol. But, says GM, ''the current use of methanol blending in gasoline can pose problems if used in today's cars over an extended period, even at low methanol concentrations.''
In its current owner's manuals, GM warns motorists not to use alcohol blends that are more than 10 percent alcohol, and to make sure that a cosolvent is used.
Arco, stung by the competition, is raising its octane rating and spending several million dollars advertising that its gasoline with methanol is not only equal to, but better than, unleaded gasoline without alcohol. Further, Arco contends, its gasoline ''contains the precise methanol blend that reduces exhaust emissions.''
Just a decade ago, when the introduction of catalytic converters on cars required the national introduction of unleaded gasoline, there was no end of confusion and debate. The methanol-or-no-methanol question is proving a replay of that debate, in a minor way.
While few drivers will ever even see the gasoline tanks in the new GM luxury cars, they are one solid proof that the methanol controversy continues.