What should I be paying?
UK prices currently start at £108,165 for the SL43 Premium, which is exactly the same as the SL43 Touring (a different, more relaxed, trim style). It's bruisingly expensive but at least it's well-equipped: Airscarf and heated, cooled electric seats, Burmester surround sound system, that tilting central screen. Oddly, the full driver-assist package is an option.
Then there’s the SL43 Premium Plus and Touring Plus twins (the same car, more kit including massage seats, heated wheel and HUD), both for £117,165.
Once you’re into the V8/4Matic all-wheel drive arena, you’re looking at £147,715 for the SL55 Premium Plus and Touring Plus (the only grades), before jumping to £169,308 for the SL63 Premium Plus and then the SL63 Performance - currently top of the SL tree - for £176,805. It's hard to imagine Mercedes's justification for the steepness of that price walk.
Pretty much every model is well-equipped and state-of-the-art in standard form, but as ever many tempting cosmetic options are there to personalise the experience and bolster the Mercedes coffers. It all depends on how much chintz you want to add. Even so, the extent of personalisation pales beside a Porsche 911, where you could lose a whole day to the configurator.
As for – shock, horror! – the practical side, it's a WLTP economy of 31.1mpg for the basic 43 RWD which drops by 1mpg for the Premium Plus and Touring Plus versions, presumably because they’re a little more laden with kit.
The SL55 and SL63 apparently both manage an official figure of 21.5mpg, which either reflects well on the ’55 or badly on the SL63 depending on which way you look at it; neither will see more than 20 in the real world. TG registered a maximum of 16mpg on a cold winter’s day, but that was all relatively restrained road driving: these are not going to be cars for those counting the pennies.