Some letters are faster than others. ‘R’. That locks straight into racing. ‘I’ works well on hot hatches, but ‘S’ works on anything. Jag has teamed S with R for its ultimate XF, and Merc has now glued it to the rump of the E63 AMG.
In the Jag, S means an extra 39bhp, 40lb ft and £14,580. Adding S to your E costs £9,995 for gains of 28bhp and 59lb ft. The end result is that the Merc, although a little more pricey, edges this contest on paper: 577bhp, 590lb ft. These are huge numbers, in turn creating some small ones: 0-100mph in 8.5secs. A near-three-second lead over the Jag at 150mph. One word describes the Merc: pulverising.
But there’s so much more to this contest, not least the way they behave under acceleration. This is the Jag’s forte. It’s supercharged, so needs no time to build up a head of steam. After the shock of that initial surge, it flatlines, and as it’s not backed up by an intoxicating soundtrack, there’s no reason to hold on for higher revs.
In the Merc, it’s all about the astonishing ramp up. It makes you wait a little, then delivers a thump of such brutality, along with an equally savage V8 war cry, that you never want it to end. But it does, the limiter calling a halt at only 6,000rpm. Too soon.
Make sure not to venture into manual shifting with the Merc’s paddles. You’ll forget to pull the upshift until too late and so headbutt the limiter. In fact, neither ‘box is at its best in manual. Best to put them in S, and let the software sort it out. The Merc’s is even more scarily predictive than the Jag’s and delivers a mesmeric exhaust flutter on shifts.
And I think that’s the difference between them. AMG understands exactly what a super-saloon needs to deliver. The Jag hasn’t quite got the focus or control. Yes, the E63 AMG is quite a severe thing. It keeps you a little bit at arm’s length and is less welcoming inside, all solid materials with no give, just a highly tasteful blend of grey leather, silver and carbon. The seats are too firm, and they make up for this with side bolsters that protrude too much.
Best to grip the Alcantara steering wheel, twist the knobs and thumb the buttons on the centre console until you get a suitably sporty mode and go for a drive. It’s impossible to completely escape the engine, even when cruising - it’s always there, the car’s heartbeat, as deep and bassy as an earthquake. The suspension has little of the Jag’s calmness, but neither ride nor refinement are uncomfortable.
For all its exterior stealth, it’s the tighter, tenser E63 that delivers the driving experience you expect to get from the more flamboyant XFR-S. I prefer it this way round, stealth overlaying madness. I’d understand if you didn’t, but I’d still say you were wrong - Merc understands the super-saloon game better than anyone. Of course, if you’re spending £80k, your options aren’t limited to four doors…