Parked side-by-side, the square-jawed BMW looks cleaner and meaner than the tall, rounded Jag. But, and this is important, the S-type has more distinguishing details and a beefy, Q-car look that sets it apart from lesser S-types more effectively than the M5 distances itself from its own puny brethren.

Having just emerged from the Jaguar, it's clear the M5's interior just shades it for outright quality, but it is beginning to look its age. Optional Nappa leather looks and feels softer and more natural than the harder, artificially textured Jag hide, but it's the S-type that has the sportier ambience thanks to those excellent seats. One element of the M5 I do prefer is the instrument binnacle, which contains classier-looking round dials, as opposed to the crescent-shaped items in the Jag.

It's been a while since I've driven the M5, and it's funny how your memory can deceive. I would have laid large amounts of money on it feeling firmer than the S-type. I'd have been out of pocket. Not only does the BMW seem softer and more inclined to roll, but it also seems to have slower steering and spongier brakes. The engine, however, is as magnificent as I remember, and shades the Jag's motor for response and smoothness. It also sounds far more appealing, thanks mainly to the lack of supercharger whine.

It's nice to get stuck into the M5's six-speed manual 'box after a day of seamless self-shifting in the Jag, and the added control and instant accelerative punch make you feel immediately connected to the big Bee-Em, even if the gate isn't that precise.

On roads that didn't see the Jag's DSC light flicker once, the M5's stability system cuts in on several occasions, especially over slight crests. The chassis obviously has a harder time containing 400 horses than the equally powerful S-type, something that becomes very clear when you disengage its DSC. Select second gear (or third if the corner's a bit more open) and the M5's tail submits to the power much earlier than the S-type's. Perhaps as a result of this earlier breakaway the M5 is an even more natural and smoothly progressive oversteerer than the Jaguar, which in turn makes it more fun if you decide to be a hooligan. The downside is that you either have to tolerate the more frequent interruptions of DSC with the system engaged, or switch it off and remain ever ready to apply an armful of corrective lock.

We're attacking roads that I have become reasonably familiar with in the S-type. Hayman is up front, acquainting himself with the Jaguar but still travelling at a fair old lick. All feels fine in the M5. The normally aspirated V8's voice hardens to a deep, big-capacity bellow as it powers through the meat of third gear, but as we approach the braking zone for the first set of bends the M5 feels nothing like as keen as the Jag. The brakes lack immediate bite, which is never a good start, and while my right foot reaches for retardation the chassis has begun to lurch into the corner. It really does feel heavy and reluctant to turn in after the relative agility of the S-type, and this sets the tone for the remainder of the day's driving.

Though more entertaining through low-speed corners, the M5 just can't seem to maintain enough composure through the faster stuff to stay comfortably in touch with the S-type. Try to match its point-to-point pace and, while things remain relatively serene in the Jag, you're either itching to turn off the M5's intrusive DSC and cursing the soft brakes, or switching out the electronics and spending your time containing momentum understeer, controlling power oversteer and still cursing the brakes. Don't get me wrong, the Jag doesn't comprehensively blow the M5 into the weeds. Rather it enables a good but not exceptional driver to cover the ground at a speed that would require a committed wheelman to cajole the M5. Granted, the BMW is happier to be driven balls-out than the Jaguar, which could equate to it being the better driver's car, except for the fact that cars like this are rarely driven on the lock-stops.

In terms of outright evoness the S-type isn't perfect. Good though the gearbox is, we'd still like to see a manual, even if it sold in small numbers alongside the auto. Perhaps that's what Jag is planning for the upcoming X-type R...

But whatever the future holds, one thing is clear now: the S-type R is the best driver's Jaguar of recent years, one that can stand toe-to-toe with a car like the M5 and teach it a thing or two dynamically, without compromising Jaguar's traditional strengths of refinement, ride comfort and interior luxury. It doesn't possess the M5's raw appeal, but it's the better car, a true all-rounder. We predicted the S-type R had the makings of an evo hero. Now we know for sure. It was worth the wait.