I feel able to comment on this having had an S212 220cdi avantgarde and a few Volvos....
I bought my E class (2012) with 3k on the clock and did 42k miles in the first year. It was mainly 130 mile journeys, often 260 a day, predominantly in a straight line. Plus points were space - boot was huge, back seat a good size (although rarely used!), it cruised well and was pretty economical (averaged just about 45mpg over the year but mainly motorway driving -including the inevitable stop start and then pressing on to make up time!). Engine a bit coarse (4 cylinder) and ride could be a little harsh at time, but mine was on 18s and I would take 17s by choice.
The seats were hard. Wore well and showed no signs of wear after that mileage but not the most cosseting. Prior to the Merc I had a Volvo S60 2007. Bought that at 30k miles and sold 3 and a half years later at 155k miles. Very reliable - couple of issues in the years, one with alarm siren, known fault, and one with a suspension bush, but otherwise faultless. Liked the 5 cylinder 2.4D engine - nicer noise than Merc and more economical - but manual and saloon. The seats were perfect though and i could happily drive that 4 hours to edinburgh without stopping!
The Merc went when i got a company car (VW Passat - never again!) and then smaller and sportier stuff. Just needed to buy a dogs, station and tip car - £15 to 16k, less than 60k miles, up to 5 years old sort of thing......again, lots of long straight journeys and whilst fuel consumption wasnt crucial I dont like wasting money!
I bought an XC70 D5 AWD, It doesnt do 45mpg - the 4wd and raised ride height wont help - but I have done 600 miles in it in a weekend and I cant think of anything I would rather have been driving. And its great to be back in Volvo seats....
The weekend toy that I am looking at is more likely to wear the three pointed star however - 4 seats soft top with petrol engine!!