Like other ER-EVs such as the +Chevrolet Volt and +Fisker Automotive Karma, the A1 was designed to be driven electrically by a moderately sized battery that would provide about 30 miles of range. When the battery was nearly depleted, the a small gas engine would fire up to drive a generator to sustain the charge of the battery and keep it going.

Unlike most of the other ER-EVs we've seen, the Audi engineering team led at the time by Michael Dick took a pass on using a conventional piston engine for the range-extender. Instead they opted to use a tiny 254cc Wankel rotary mounted under the rear cargo floor. 

Unfortunately, earlier this year, top management at the Volkswagen Group decided that they no longer wanted Audi going off on engineering tangents. Instead, they would be homogenized with the work going on in the rest of the group. Mr. Dick was retired and replaced by former Porsche R&D chief and then Bentley CEO Wolfgang Durheimer. 

This week Audi revealed a revamped version of the A1 e-tron, with what is now dubbed a Dual-Mode Hybrid system. This is effectively the same system that was originally shown in the VW Golf Twin-Drive back in 2008. The main difference is that the four cylinder diesel used in the Golf has been replaced with a shorter 3-cylinder gasoline TFSI engine for the smaller A1. 

When I went to Germany for a media drive of the MK VI Golf in 2009, VW brought out one of its prototype Twin-Drive units and I had a chance to drive it. I published my report on that for GreenFuelsForecast.com. In my short drive of the car it worked well with relatively seamless mode transitions.  

As a longtime fan of the Wankel, I'm sorry to see it de-emphasized for this project. I still think it could make a great range extender and look forward to seeing further efforts with it.