Rising gasoline prices are driving up the sales of fuel efficient cars.
 That's good news for detroit automakers who are finally winning the competition with their overseas rivals in that segment of the auto market.
 General motors says in march the company sold 100-thousand cars in the u-s that got 30-miles-per-gallon or better on the highway.  
  That's a first for the company.
   G-m reports demand rose for all of its 12 models that get 30-m-p-g on the highway.  
   Even chrysler group, the u-s automaker most reliant on trucks, has also seen strong sales from its handful of 30-miles-per-gallon cars.