Most of the entries in this class have small, fuel-efficient 4-cylinder engines as their base power plants; only a few offer V6 upgrades.

That means it would be possible to use small fuel-efficient engines in larger cars.

Then came the first oil crisis, in 1973, and environmentally correct compacts with their fuel-efficient engines.

The biggest technological challenge would be developing a fuel-efficient and quiet engine, executives said.

As such it came with a fuel-efficient single-cylinder two-stroke engine.

It has more fuel-efficient engines and a greater range than its predecessor.

They had learned how to make roomy and comfortable cars with fuel-efficient, low-polluting engines.

The company that comes up with a practical electric car or a fuel-efficient engine could see its sales spurt.

How about a lighter, faster, safer and more fuel-efficient engine?

And speeding can make even the most fuel-efficient engine guzzle gas.