Audi calls it a "near-production" study, but this A4 packs a fuel-sipping 2.0-litre turbodiesel which the manufacturer claims is good for 3.99 l/100 km.
The technology concept shown at the Paris show is called the A4 TDI concept e.
The powertrain uses a direct injection TDI engine producing 88 kW and 290 Nm, giving the sedan a 0 - 100 km/h-time of 10.7 seconds and a top speed of 206 km/h.
According to Audi, this is possible while consuming under 4 l/100 km while emitting 105 g/km of CO2.
A host of details, including soft springs on the intake valves to a new heat management system, is said to improve the engine's efficiency. The fuel pump and the air conditioner's compressor have also been adapted.
This A4 is also equipped with a recuperation system that recovers energy that would have been lost when braking and temporarily stores it in a battery. A stop-start system switches the engine off when the car comes to a standstill.
Weight reduction techniques are also in place, including the use of magnesium to reduce the weight of the six-speed manual transmission with modified gear ratios.
Physically, the body has been altered to make it more aerodynamic with adjustments to the grille and underbody and a modified ride height.
Furthermore, the 17-inch tyres fitted to this A4 have a low rolling resistance and an electric brake system is used on the rear axle.
While on the road, the driver is able to access a training programme to help him drive more economically or he can use the navigation system to calculate the most fuel efficient route.