In Pelham, Alabama, Allen Apel and Lee McKee show off the 1959 Fiat they bought from the Talladega International Motorsports Hall of Fame. In the trunk, they found records indicating Shell scientists had souped up the car in 1969 to get 244 miles per gallon of gas.

Houston Chronicle

if this is true, it proves 2 things:

1)that putting fuel efficient engines in cars is possible

2)the oil industry, knowing this is true, committed a huge crime by keeping that technology a secret. that information could have created entire fleets of good gas mileage cars. but then again, that would be a conflict of interest for the oil industry, which relies on selling more gas, not less.