After unveiling the bonkers AI:Trail Concept at the 2019 Frankfurt Auto Show last month, Audi is already cooking up another electric concept. The German automaker has released a photo of its electric line-up featuring the current e-tron, the e-tron GT concept and the Q4 e-tron concept. Look closely, however, and you can spot a new unannounced model hiding under a sheet at the back previewing the next generation of Audi's electric cars.

Whereas the e-tron SUV is underpinned by the MLB Evo platform and the e-Tron GT will use the J1 architecture developed by Porsche that underpins the Taycan, the concept will showcase Audi's Premium Platform Electric platform that can support a range of body styles including sedans and SUVs. Lower-end models will feature a rear-mounted electric motor and a rear-wheel-drive layout, while higher-end models will add an electric motor at the front axle to enable an AWD configuration.

Audi says the PPE's architecture is "generally similar" to the MEB, but supports four-wheel steering, torque vectoring, and air suspension. While models based on the PPE platform will be shorter MLB-based models, they will have more spacious cabins thanks to the placement of the electric motors and the battery pack while getting rid of the center tunnel. PPE-based Audis will feature an 800-volt system capable of 350-kW charging. Different battery packs will also be available, with the largest delivering a range of over 300 miles.

While the concept is hidden under a sheet, the front has been lifted showing a new grille design for Audi's future electric cars. A separate shadowy photo shows the concept will be a sleek electric coupe with a sloping roofline.

According to AutoExpress, the unnamed concept is around the same size as the A7 Sportback, but has a slightly higher roofline due to the thicker floor required to accommodate the battery pack. An Audi source also told the publication that the concept is an "early work in progress" and that work on the front-end styling is at a more advanced stage than the rest of the car's design. There's no word yet when Audi's new concept will debut, but PPE-based models are expected to go on sale in the early part of the next decade.