German car magazine Auto Bild has the scoop on the upcoming S8, S7, S6 and RS6 models from Audi.

First up is the S8, which is expected to make its debut at the Frankfurt motor show in September.

The S8 will feature a new 4.0 liter, twin-turbo V8, developed together and shared with sister brand Bentley, with an output of approximately 500 PS (368 kW / 493 bhp). That beats the previous S8 by 50 PS but the new model will still outdo it on fuel-economy by about 20 percent. The S8 will come with an 8-speed automatic gearbox and Quattro all-wheel drive as standard.

Following on its heels will be an introduction of the 2012 Audi S6 and S7 models at the Los Angeles auto show. Both the S6 and the S7 also get the new 4.0 liter V8, with 440 PS (324 kW / 434 bhp) and 470 PS (346 kW / 464 bhp), respectively. Although, Auto Bild doesn't specify whether they get naturally-aspirated, single-turbo or twin-turbo variants of the unit.

Finally, comes the RS6 which will get that 4.0 liter, twin-turbo V8 too as Audi appears to be making the most out of the power plant. The unit will be configured to deliver 580 PS (427 kW / 572 bhp) and keep the model competitive with its arch-rival - the recently unveiled BMW (F10) M5 which comes with 560 PS (412 kW / 552 hp) and 680 Nm (502 lb-ft) of torque.

We've also previously reported that an RS7 is expected with that 4.0 liter, twin-turbo V8 tuned to around the 600 PS (441 kW / 592 bhp) mark.

Auto Bild says the RS6 will launch in late 2012.

Gallery: Upcoming Audi S8, S7, S6 and RS6 details emerge

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