Small minds turn in tight circles. You won't change an opinion so deeply held, but you can encourage people reading a rant to do their own research. There are some negative reports here, but this is hardly an unbiased setting. Add the rant and the love and divide by two.
I typically read the glowing reviews and then the trash talk so I can measure the two extremes, then look for moderate views that support either argument. If someone had a mechanical problem and got no dealer support, is it a common complaint? If there are repeated posts about the same problem, one check in the negative column.
Overreaction of the supporters doesn't always counter the nay-sayer's comments. Could just be a small band of very vocal fanatics (root of the term "fan"). A measured and firm response to all (most) negative comments and on to the fun stuff.
Did this guy not look at the car before he bought it and realize there was no back seat? Don't blame MB for your failure to shop for financing. And the price was in the window, along with the EPA gas mileage estimates. Sounds like the only legitimate complaint is the sore back and that sounds like it's the result of where he has his head stuck. (Which might also explain why he didn't see the lack of a back seat, the price, or the mileage.)