A-Class – Tries to be practical, but completely outclassed by much cheaper rivals in most other areas. It’s a blend of mediocre dynamics matched by mediocre performance. It doesn’t even offer superior comfort. The only thing separating it from the pack is the MB badge on the grill. Sorry, you're wrong here. The A-Class is a superior contender in this class offering more than enough appeal to most buyers. The emphasis in this class is not SPEED, but FUEL ECONOMY, so nobody cares if the cars here are "slow". Besides, the A200 and A200 Turbo and A200 CDI are more than fast enough, I've driven them. Sure, it's pricey but that's what you pay for when you get a Mercedes: image. I don't know where you got the idea that the A-Class has "horrible driving dynamics". Drive the car first, then comment or don't listen to what magazines say. I've driven many new A-Classes and they handle really good. Predictable and safe. I rank the A-Class as one of the "sportiest" Mercedes' out there, even though the car doesn't try to be sporty. If you're talking about the old A-Class, yes, that car sucked.
B- Class – What really was the point here? Could they not have built a proper 1 or A3 rival? The A-class already appeals to the practically minded buyers. The B is utterly pointless really and seems to have cannibalized the aging c-class’s market. Yes, C-Class sales have been cannibalized by the A and B-Classes, but the B-Class is a pretty appealing car in Europe. The driving dynamics don't match that of the A-Class, but it's appealing because of its size (important for Europe) and practicality. When I worked for an MB dealer last summer, there where many people trading in their Mazda 6's etc. for one. Personally, I like the styling but the drive is pretty wobbly and probably geared towards older buyers.
C-Class – The facelift did very little to improve the appeal of this vehicle. It clearly looks a generation behind the A4, 3 and IS. Wrong again, the C-Class has become very appealing after the facelift. The transformation of this car was phenomenal. The pre-facelift C-Class was a mediocre piece of machinery, not the facelifted one. The car feels noticebly more solid, handles nearly on par with the BMW 3-series in everyday driving and the new engines have made the C-Class very appealing. And I've driven a bunch of older and new C-Classes to really feel the difference. The C-Class now ranks as one of my favorite MB's. In Europe, the new C-Class has won several comparo's over the BMW 3-series because it's been improved that greatly. I can see why it's not appealing in America when you have all this competition over there.
E-Class – The one MB design that still captures some of the past’s MB’s elegance. Lackluster quality has damaged its reputation hugely however. Quality is fine, reliability is the issue here.
S-class – Perhaps still engineered like no other, but where has the beauty and splendor gone? Design is subjective. But you should know that MB addressed the engine issue and made the new V8 a smooth runner. C&D even said it was superior to the Lexus 4.3-l V8 in smoothness, perhaps even better. Having driven the new W221 S500, I have to agree. This engine is powerful and extremely refined. MB is making a comeback.
M-class – Not much to complain about really, but still lacking some key tech advances (Distronic, reversing cameras, lingatronic). Does it raise the bar high enough to remain competitive against the new X5? Unfortunately this doesn’t seem likely. The X5 is a SPORTS SUV, why is it all of a sudden the "benchmark in its class"? It's not: the Cayenne is when it comes to sports SUV's. The M-Class doesn't try to be a sports SUV. I've driven the new and old M-Classes and the new M-Class is pretty solid onroad. It's not on the same level as the X5 dynamically, but it's pretty solid and easy to drive for most people. Where the ML kills the X5 is offroad. The X5 is simply no match for the ML offroad because BMW emphasized the onroad-drive, not offroad.
R-Class – Looks very much like the ugly duckling of the MB range from the pictures (I am yet to see it in the metal). Is it really so different from other people movers though? Appealing and practical, but ugly, I agree.