Range extenders are a compromise because they allow for the drivetrain to be lighter than full plug-in hybrid systems while similarly boosting fuel economy. General Motors' Chevrolet Volt is the most notable model with a range extender, and BMW makes a version of its i3 EV with a range extender. Karma, the successor company to luxury automaker Fisker, will also resume building cars with range extenders.
PSA will unveil about a dozen new hybrid and plug-in models within the next five years in order to address stricter fuel-economy and emissions mandates across Europe. Notably, French competitor Renault has developed a two-stroke range extender but hasn't used it on any model, instead going the electric-vehicle route with sister company Nissan.
Peugeot earlier this month came clean about the realistic fuel-economy figures for some of its engines. The company tested 28 models across its Peugeot, Citroen, and DS lines, and found that the cars, when loaded down with luggage and running climate-control systems, get about 40 percent lower fuel economy than advertised. So while neither Peugeot nor Aquarius is divulging how much the range extenders can reduce gas use, let's just say that Peugeot may be looking to recapture some of that "lost" fuel efficiency.