A likely replacement of the 1,500bhp Veyron has been seen testing on international roads. This is the first evidence that the replacement for Bugatti's nine-year old Veyron is finally under development.

Despite having looks similar to the current car, there are clues as the shape of the new model, particularly the NACA-style air ducts in the roof, and the new rear window and engine cover details.

Sources told our sister publication Autocar UK that the new car’s styling has been signed off by the Bugatti design team, allowing full-scale road testing to commence. This test mule is thought to be fitted with the new-generation Bugatti engine, which is expected to well exceed the 1,200bhp output of today’s Super Sport and Grand Sport Vitesse Veyron models.

According to the latest inside information received at Autocar UK, the new Veyron will see the 8.0-litre W16 engine updated with a direct fuel injection and even electrically-assisted turbochargers.

The biggest change, however, is expected to be the adoption of hybrid assistance, with an electric motor incorporated into the new transmission, which will be backed up by a small battery pack. Significant weight saving is also planned for the new car.

The upshot is that the engine should be able to produce just short of 1,500bhp, though its torque output will be pegged back to 152.1kgm to ensure the longevity of the gearbox. With greater power comes the need to manage even greater levels of heat, which probably explains the large openings in the new car’s roof and engine cover.

The arrival of the new car was partly delayed by the need to “fit in with other (VW engineering) programmes ”, according to another company insider. The presence of a VW steering wheel in this test car suggests that the Veyron will probably be sharing much of its electrical architecture with MQB-and MLB-based VW Group cars, both of which support a wide range of safety equipment, including automatic braking and cruise control.

Brand boss Wolfgang Dürheimer has told Autocar UK that the company was determined to keep its world speed record for a production car. “We know there are challengers, but we are determined to do our homework on this.”

This means the production version of the new Veyron must exceed the performance of the Super Sport World Record Edition's 431kph top speed and 0-299kph time of 2.5sec. Sources say, the Bugatti development team has its eyes on a new top speed of 460kph.

It's thought there are eight Veyrons left to be sold out the current production run. An expanded factory should be able to build the new car more quickly, though the total production run of the second generation is also expected to be limited to around 450 units.