The two German car makers are using lightweight materials and electric drivetrains on their concept cars.
BMW and Audi go head-to-head in featherweight electric car fight
Two of Germany's biggest brands have done an about-face on their performance and luxury roots - at least partially - and introduced two slightly different takes on the tiny, electric city car.
BMW and Audi are both using advanced composites and materials and utilising electric drivetrains for their concepts in a bid to cut weight and develop more efficient electric and battery systems.
First it was BMW; earlier this month, it took the wraps off of its new i sub-brand of electric vehicles. The 2013 i3 and 2014 i8 are both based on what BMW calls its LiveDrive architecture, a carbon fibre-reinforced polymer (CFRP) tub chassis that is designed for higher strength and lower weight than conventional steel.
Officially the cars are concepts, but they display the type of technology and styling that the vehicles will sport when they are scheduled for production. The smaller i3, which is about half a metre shorter than a Nissan Leaf, is all-electric and will have a range of about 150km on a single charge. Meanwhile, the larger, sportier i8 is a hybrid that combines an electric motor with a 3.0L petrol engine that puts out a total of 349hp and produces a top speed of 250kph. Both cars are rear-wheel drive and seat four passengers.
"This vehicle will mark the launch of the first volume-produced car featuring bodywork largely made of carbon," says Klaus Draeger, member of the BMW board responsible for its development. "It's a revolution in automotive design."
In addition, BMW is focusing on new mobility and navigation services along with car and parking-spot sharing schemes with its new i series.
Never one to let BMW have any territory to itself for long, Audi is about to crash its Bavarian rival's new i sub-brand with a revolutionary, clean, prestige city car of its own.
Taking up even less real estate than BMW's i3, the Audi UrbanConcept is a semi-open wheeler design narrow enough to be easy to drive and park in crowded city streets.
With two offset seats, the UrbanConcept will be fully electric and will drive its 21-inch wheels via two of Audi's e-tron electric motors.
The radically styled UrbanConcept will be built from a combination of aluminium and CFRP.
Where BMW has launched the i as a sub-brand, Audi has confessed it is more likely to reintroduce the A2 - still an urban favourite in the European used-car market - as an eco-friendly, city-car range, with the UrbanConcept leading the way.
The UrbanConcept shares no architecture or components with any other production Audi and its taut, aggressive lines are also said to provide hints to the future design language of Audi's mainstream lineup.
Besides its cabin, the best features of the UrbanConcept are its stand-alone wheels, which allow it to have short overhangs.
While the top of the wheels will be covered, they'll also be protected visually by blinking LED lights and will have brake energy recuperation to extend the range from the lithium-ion battery pack.
The passenger compartment will be, like the i3, made from CFRP, which Audi and its supercar arm, Lamborghini, has been massaging into cheaper and faster production for more than 30 years. Both the seat bases are moulded into the UrbanConcept's carbon-fibre body, and the driver can simply adjust the pedals and the steering wheel, along with the backrest angle, to suit themselves.
Audi insists the odd, offset seating positions, with the passenger seat to the side and slightly behind the driver's seat, will provide plenty of space while keeping the cabin narrow, and both occupants slide the large, single-piece roof back to enter the car. The car's light weight promises to lend the sleek UrbanConcept with reasonable straight-line performance and allows it to use a smaller battery pack than a converted production car.
All three of these concepts are expected to appear at the Frankfurt motor show next month.