This should be the point where concluding thoughts are collated on both, the positives and negatives of each car weighed up and a verdict narrowly favouring one is reached.
In this comparison, that won't happen. Assessed purely as sports cars, the Mercedes is comprehensively beaten by the Jaguar across the board. The driving experience is just more honed, involving and composed, leaving the Mercedes to feel rather remote and lacking finesse.
The F-Type isn't perfect though, and the SLK isn't terribly flawed. As convertibles, the Mercedes trounces the Jaguar. Roof up, it's more refined and better insulated and a good deal less blustery with the tops lowered. Treated as a kind of V8 muscle car roadster, the SLK55 is rather good.
But we've come to expect more from AMG products than brute force now, and certainly crave something extra from a sports car. There's no doubting it has a fabulous engine, but cars like the SLS and C63 have shown that AMG can now deliver dynamically in addition. The SLK just doesn't reward like those cars.
The Jaguar definitely does, and then some. Driving at speed with the roof down shouldn't be so damn noisy, the interior needs a few finishing touches and we still have an issue with a 1,600kg sports car. But it's just such an absorbing car to drive at all commitment levels; it will mooch along all day if you want people to look, but also scream its way to 7,000rpm in a flurry of gearshifts when you want nobody watching. It's fabulous.
So having driven every variant of the F-Type now (you haven't watched Chris Harris in the V8 yet? See here) we can say categorically that the new Jaguar sports car is very good indeed. Next year's Coupe promises more of the same, a car we can't wait to drive.