Will new, 83 m.p.g. car save Britain's king of road?

The success of much of British industry may hinge on a single statistic: 83 miles per gallon. That figure, leaked Sept. 9 from the Department of Transport amid squeals of delight of BL (British Leyland) dealers, is what Automobile Association tests show their new Mini Metro can do at a steady 30 m.p.h. Tests show the Metro is equally impressive at other speeds.

Those figures may be just what the nationalized automaker's new "hatchback" needs when, on Oct. 6, it reaches for a fat slice of the domestic ar market now held by such foreigners as the Fort Fiesta (made in Spain) and the Datsun Cherry.

Nobody minimizes the importance of that slice. Many auto experts believe the future of BL hangs on the Mini Metro's success. They note that BL's no-nonsense chairman, Sir Michael Edwardes, recently announced a corporate loss of $:182 million ($437 million) for the first half of 1980.

$:275 million ($660 million) was invested in a new plant and design for the Metro. If the investment pays off, sales could produce much-needed cash for the firm, revive customer confidence in a line of products that even loyal Britons detour away from, and convince government ministers to pour more funds into the corporation's future.

But if the venture fails, observers here foresee the rapid demise of BL's mass-production car business -- the bread and butter of any automaker -- and of its 18,000 dealers nationwide. The impact of that failure would be felt widely. The automotive components manufacturers in the struggling British Steel Corporation (that supply steel to BL), the freight-hauling areas of British Rail (that move coal and coke for British Steel), and the National Coal Board would all feel the impact.

The Metro's miserly appetite, say BL spokesmen, is due to no particular breakthrough. It is simply the result of paying close attention to such things as aerodynamics, weight, and rolling resistance, as well as providing high gearing and special engine tuning, which facor economy over high performance. While they recognize that nobody ever drives a steady 30 m.p.h., they tout other figures: 58.3 miles per (imperial) gallon at 56 m.p.h., and 41.5 miles per gallon in urban conditions. rate loss of $:182 million ($437 million) for the first half of 1980.

$:275 million ($660 million) was invested in a new plant and design for the Metro. If the investment pays off, sales could produce much-needed cash for the firm, revive customer confidence in a line of products that even loyal Britons detour away from, and convince government ministers to pur more funds into the corporation's future.

But if the venture fails, observes here foresee the rapid demise of BL's mass-production car business -- the bread and butter of any automaker -- and of its 18,00 dealers nationwide. The impact of that failure would be felt widely. The automotive componenst manufactuers in the struggling British Steel Corporation (that supply steel to BL), the freight-hauling areas of British Rail (that move coal and coke for British Steel), and the National Coal Board would all feel the impact.

The Metro's miserly appetite, say BL spokesmen, is due to no particular breakthrough. It is simply the result of paying close attention to such things as aerodynamics, weight, and rolling resistance, as well as providing high gearing and special engine tuning, which favor economy over high performance. While they recognize that nobody ever drives a steady 30 m.p.h., they tout other figures: 58.3 miles per (imperial) gallon at 56 m.p.h., and 41.5 miles per gallon in urban conditions.

Armed with these numbers, BL is mounting a massive campaign to pave the way for its new four-wheeled savior:

* In a $:1 million ($2.4 million) promotional effort BL has taken its dealers on a luxury cruise to the Isle of Man to see the still-secret Metro in action. Pictures of the car gliding unnoticed through streams of city traffic are already beginning to crop up in the press.

* Sir Michael has called on the Department of Trade to slam the door on imports of Fords from Spain. Adding his voice to those here calling for import barriers on everything from apples to textiles, he said, "We are virtually prohibited from exporting to Spain, while cars made there flood into the British market."

* British carmakers have won a continuation of a gentlemen's agreement with Japan to limit Japanese car imports to about 11 percent of the annual British market. So far this year, the figure has exceeded that level, which means that imports should fall of nicely just when the Metro hits the showrooms.

The Mini Metro itself will be sold strictly in Europe. BL has no plans to market it in the US, in part because expensive alterations to the bumper and engine would be required, according to BL officials in the US.

But Sir Michael is hardly yielding to optimism. The next 18 months, he predicts, will be especially tough, until the widely prophesied upturn in the car market arrives at the end of 1981.

Nor will the Metro itself solve BL's difficulties. Some major shifts in the industrial balance of power may be in the offing with from pouring $3 billion into the Escort (its new "world car"), with 1 millioin Us autoworkers out of work and US carmakes suffering unprecedednted financial losses, and with the Japanese taking ever-larger bites from American and European markets.

So BL is not sitting on its hands. It is already looking beyond the Metro to the Bounty, built by BL under license from Honda. Also ahead are two new code-named prototypes -- the 1C 10 (a five-door hatchback scheduled to be introduced in late 1982) and the AM2, a conventional sedan aimed at the fleet market.

"The 1C 10 is even more critical than the Metro to BL success," says Sir Michael, who is angling for more government, cash (beyond the $:130 million promised during 1981-83) to finance the new models.