The rivalry is a clear indication that the race is on between carmakers eager to conquer emerging markets for efficient, light-weight electric cars.
BMW is investing heavily in city cars, pointing to how the number of cities with a population of more than 10 million people rose from 83 in 1950 to 468 in 2007 and predicting dramatic growth in the years and decades ahead.
Volkswagen Group is hot on its heels. Its luxury subsidiary Audi will unveil a carbon fibre reinforced polymer two-seater electric city car at the Frankfurt motor show.
And earlier this year VW unveiled a similarly constructed XL1 concept car, which it said could travel 503km (313 miles) on a gallon of diesel, emitting just 24g of carbon dioxide per kilometre travelled.
Other carmakers are getting in on the act too, most notably Daimler - owner of Smart, Mercedes and Maybach - which in January this year formed a joint venture with Toray Industries to produce carbon fibre reinforced plastic car parts.
Increasingly carbon fibre parts are being used to make more conventional models lighter to improve their weight to power ratio.
In small city cars, this means less power is needed to propel the vehicles forward. In larger, sportier cars it means existing engines will have less weight to lug around so their speed and performance improve.
McLaren's MP4-12C sports car, for instance, is built around a highly rigid carbon fibre monocoque, which means its relatively small engine still delivers tremendous speed and acceleration.
A Lotus Evora sports car with carbon fibre interior and a composite body was unveiled at the Geneva motor show in March.
And Europe's fastest production car, the Koenigsegg CCXR Edition, has a carbon fibre body.
Eventually, such hi-tech, light-weight components may also make their way into mainstream cars.
And it is then that this technological breakthrough will have a real and major impact on the overall emissions and fuel consumption of ordinary cars.