new E63 AMG. Visually the same as its predecessor the only real change you'll see from the outside is the switch from 6.3 V8 to V8 Biturbo on the front wings (broader to contain the bespoke, 56mm-wider AMG front axle). This new 5.5-litre engine has a very different character to the much loved M156 6.2 though. This is engine downsizing then, in a very AMG fashion.
So to those M5 comparisons. The BMW's V8 is a comparatively modest 4.4 litres but develops 560hp and 501lb ft, the latter between 1,500 and 5,750rpm. AMG's manages 525hp and 516lb ft, again in a huge fat wedge between 1,750 and 5,000rpm. One nil to Bavaria then? Not necessarily. Because if your ego can't quite deal with that slight power imbalance Mercedes will gladly relieve you of a further £6,495 (£5,895 for the estate) to raise power to 557hp and torque to a frankly ludicrous 590lb ft. Oh, and you get red brake calipers too. Bargain.
In terms of performance even the standard E63 pips the M5 to 62mph by a tenth (4.3 seconds versus 4.4) with another tenth off with the Performance Package. Both have seven-speed automated gearboxes, the M5 a DCT and the Mercedes a seven-speed auto with AMG's MCT lock-up clutch instead of the regular torque convertor. Even the emissions and fuel consumption figures are to within fractions of each other.
So much for the spec sheet comparisons, because in this battle it comes down to character.
It's crucial too. Because AMG set itself one hell of a hurdle replacing the wonderfully charismatic 6.2 V8. Offering the 5.5 in an estate body is a good start, there always being something rather cool about mega-horsepower wagons.
over-specced press carshas come up recently, but if you like the look of the E63 wagon you need to keep a close eye on this particular car. Boasting a heroic £90,960 price tag someone had some real fun here, loading it to the gunwales but not passing the opportunity to tick the box marked 'AMG locking differential' and adding another £2,450 to the price. Given the rate of depreciation on some AMGs, this car is going to be a bargain for someone a couple of years down the line...
A future 'Spotted' in the making
And what a treat they'll be in for. First impressions of the new turbo V8 are that, try as it might (and it tries really, really hard) it can't quite match the instantaneous, linear response of the 6.2, or its hard-edged engine note.
It does, however, have that mind-warping elasticity and bigger initial wallop, peak torque coming in at 1,750rpm rather than 5,200rpm as before. Frankly it's a bit daft, what seems like a moderate squeeze of the gas on a motorway slip road seeing you arrive in lane one in a blaze of brake lights and 'oh cripes, not again' at the numbers that have just appeared on the speedo.
There's a fluidity and natural ease about all E-Classes that survives the AMGing process too. The steering is beautifully weighted and geared, the extra track and negative camber at the front end giving it useful extra bite that can be neatly balanced on the throttle with the optional diff. A shade off two tonnes (the saloon is 105kg less) the E63 is never going to be nimble on its feet but its ability to bully the road into submission is frankly astonishing.
Mix and match
Unusually AMG uses steel springs up front and self-levelling air ones at the back and though the system is balanced enough that you'd never know it doesn't feel quite as natural as the C63. Nor will you likely feel moved to go beyond the standard setting and explore the two harder ones.
The E63 - especially this one with its £90K pricetag - is an exceptionally ludicrous piece of kit. But it's AMG's ability to make it feel simultaneously so sensible that so appeals. Over to you M5...
MERCEDES E63 AMG ESTATE
Engine: 5,461cc V8, twin-turbo
Power (hp): 525@5,250rpm (557@5,250 with Perf. Package)
Torque (lb ft): 516@1,750rpm (590@2,000 with Perf. Package)
0-62mph: 4.3/4.4 sec saloon/estate (4.2/4.3 sec with Perf. Package)
Top speed: 155mph (limited, 174mph/186mph saloon/estate with AMG Driver's Package)
Weight: 1,840kg/1,945kg saloon/estate
MPG: 28.8/28 saloon/estate (NEDC combined)
CO2: 230/234g/km saloon/estate
Price: £74,895/£76,895 saloon/estate, £90,960 as tested