Hot new Mercedes-AMG E 63 saloon and estate could have up to 600bhp to compete with BMW M5.

Mercedes-AMG is adding the finishing touches to the new range-topping E63. Recent spy shots show both saloon and estate prototypes undergoing final testing ahead of an arrival towards the end of the year.

If you’re thinking Mercedes-AMG has already had its hands on the E-Class you’d be correct, but the 394bhp E43 was introduced to bridge the gap between the standard saloon and this full-blooded BMW M5 rival.

Whereas the E43 is powered by a 394bhp 3.0-litre twin-turbo V6, the E63 is likely to switch to the larger and more powerful 4.0-litre twin-turbo V8 from the AMG GT supercar. That engine currently produces 503bhp, but engineers are expected to crank that up to around 550bhp in order to keep pace with the 552bhp M5. However, Mercedes-AMG could also introduce an even faster S version boasting around 600bhp.

To help contain the power, expect the E63 to switch to a rear-biased four-wheel drive system – like that found on the E43 – which will be driven through a seven-speed automatic gearbox.

There will be changes to the suspension which will be lowered and stiffened to boost agility, while beefier brakes will also be housed under larger alloy wheels.

Take a closer look at the spy shots and you can pick out some further visual tweaks, too. The vents on the front bumper are wider and deeper allowing the engine to breath more feely, while at the rear four-tailpipes hint at the performance on offer.

The E63 will also be unique in the respect that it will be offered in both saloon and estate bodystyles – the Audi RS6 is estate only, while the BMW M5 is strictly a saloon. Prices should start from around £85,000.