Smart cars could be achieving 100 miles to the gallon with CO2 emissions of less than 80g/km if a revolutionary new hybrid engine developed by DaimlerChrysler and British firm Zytech gets the go-ahead.

The concept, called smart hyper, hits achieves the mpg rate by using an electric motor to pull away and at low speeds, with a diesel engine cutting in later.

The energy supplied by the electric motor to the drivetrain also helps its 0-62mph time - almost two seconds less than the conventional diesel drive at 17.8 seconds. The concept will be unveiled at the Frankfurt International Motor Show later this month, and may make it into production by 2004 if the idea is taken up.