Possible evidence of a new collaborative plan between BMW and Fiat has come to light today, in the form of a rumour that the two European marques will develop a line of ‘city cars’ on a shared platform.

According to British rag Auto Express, the new city cars will be an ultra efficient line, with a focus on breezing through tough new European legislation on CO2 and other gas emissions, locked in for 2012.

Aiming to get the cars into showrooms a year earlier than the legislation will be enacted, the two companies are supposedly shooting for a 2011 production date, with a concept to debut at the Frankfurt Motor Show this year.

Both cars are expected to feature rear-mounted engine setups, with seating for four.  Competitors would include the Toyota iQ, the Volkswagen Up!, and a possible offering from Hyundai.

An electric drivetrain would feature, possibly utilising hub motors in each wheel, powered by a thin lithium ion battery pack beneath the seats.

Both the BMW and Fiat models would feature extensive use of light materials, including aluminium, carbon-fibre, and plastic. 

While both companies cars are expected to share the same platform, only the BMW model would see US showrooms. 

Given Fiat’s renewed Aussie presence, we could possibly see both sold in Australia.

At this point the names remain unconfirmed, but pundits are hopeful the cars will wear the Isetta and Topolino badges, which will be familiar to enthusiasts of the old school.

The Isetta stood out as one of the most successful ‘microcars’ produced in the years following WWII.  The Isetta name and design was owned by Iso SpA and licenced to a number of companies in different nations, one of which included BMW.

The future German giant took the name to new heights, re-engineering much of the car to make it a true BMW (albeit an incredibly small and quirky one).

Fiat’s Topolino (also the Italian name for Mickey Mouse, meaning “little mouse”) was in fact the first Fiat 500, at the time one of the smallest cars in production.

The Topolino was launched in 1937 and received only minor changes to its design and the 569cc four-cylinder engine before the Fiat 600 was launched in 1955, forming the basis for the Fiat 500. 

In essence, an all-new Topolino would be a new version of the same car that eventually evolved into the Fiat 500, for which there is also a new version today.  Cripes!