I bought my ML55 used a little over a year ago for $20K. It is a one owner and had 50K on it when I got it along with all service records. The things that everyone complains about (poor build quality causing rattles, etc) had been sorted out by the time I got it. For close to 70 large I have to agree that some of the interior pieces are pretty cheesy such as the flimsy glove box door, etc. For $20K it's the best vehicle I have ever seen. Power, traction, looks, comfort etc are all unbelievable. I would highly recommend one. There is nothing in the mid size SUV arena that comes close to the ML55. I sold my 91 Porsche 911 and my 2000 Durango and bought the Benz. It satisfies the sports car feel and can also run to Home Depot or pull an 18' ski boat with no problem. It also only takes up one garage space. The only drawback is the fuel "economy". The 5.5 liter AMG V8 is worth the price of admission for sure. It's actually close to what I got in my 318 Durango around town and a little better on the highway. I average around 14 MPG overall.

Now, I don't own one of these myself although one of my collegues does and I have often been privelidged to drive it with him. The Mercedes ML 55 is visually very impressive, with large alloys and an improved body kit. It combines sports appeal with that of a serious off-roader, which is pleasing. Inside the cabin is very well equipped, with most of the toys you would expect from a £50k+ machine. The engine sounds solid and throbby on start up and it drives very well, although the ride isn't quite as comfortable as my Merc E320 estate. The perormance is perhaps this car's main weapon: 0-60 mph in 6.8 seconds and 145 mph top speed. This, along with a price tag of £54,000 puts this car into some serious competition. It really does feel fast- especially on the motorway where you just floor it and watch the scenery blur by with the demonic growl of the V8. Acceleration is good at any speed, and torque is aplenty which allows the ML to push on without too much of a pause. From the lights this massive block can often shame smaller, lighter convertables as well as basically any large off-roader. So then, it looks great, it is well equipped and it goes like hell. So are there any bad points?
Well actually, there are. According to my good friend the vehicle suffers many problems, most of them electrically. These can be sorted, but they are very frequent. The mechanics are also not quite up to scratch either, and the overall quality of the car is slightly dissapointing for something so expensive. Interior space, while being quite good is far from class-leading, and the handling, although improved over the stadard ML models is still not good enough to compete with sports cars, or even large executive cars. My friend confirmed this with an amusing tale of him chasing a V6 Mondeo through the country side of East Sussex: On the straights he would easily catch the smaller saloon but on the twists the Ford had the advantage to the extent of pulling away, so that when he caught it up again on the straights there would be another turn. However, as the tale goes, the Mondeo eventually joined a dual carriage way where he was also going, but as my friend prepared to make up for the humiliation on the twists and cream the Mondeo, he had to stop at a fuel station as the tank was empty. The Ford sped away while it still could, victorious against a £54k machine. The ML55 drinks liquid like a devoted alchoholic. My friend says he struggles to make 20 mpg while driving nicely and this drops to a laughable 12 when he flexes his right foot. So then it is very fast, looks good, is well equipped and nice enough to drive.
But it is sometimes unreliable, is mechanically flawed, despite good handling it cannot out do smaller, cheaper driver's cars, isn't quite as well made as it's price suggests, and there are two more problems. Problems which are almost certain to be the downfall of this once proud and dominating beast. They are called the BMW X5 4.6iS and the even more demonic Porsche Chayenne Turbo. These are newer, better quality, sharper hangling and with the Porsche, faster then our hopeful Mercedes friend, who is suddlenly looking dated and dynamically behind the new contenders.
MY friend, however, agrees with me and so has taken the appropriate course of action to fix the problem: He now has a Chayenne Turbo on order now as I speak...

I have had two x5 s then changed to a second hand Mercedes M Class ML55 AMG ,It absoloutly blows them away!. The first thing I had done to this vehicle was have it converted to lpg fuel, cost would not be cheep. It averages 12 mpg round town but on lpg its fine motorway mpg at 70 mph returns 20 so its like getting 40 mpg when using gas, but dont forget this has 350 bhp and it shifts. I have done track days and 140 + is no problem but then I have also been to off road events (I have a jeep wrangler which I use off road )and taken the ml off road< its great electronics made it almost a boring drive up and down steep inclines, wading was no problem you just have to watch the bumpers on the amg as they are lower than the standerd ones but it performed superb. on the road its a superb cruiser and every now and then you can out sprint the 30 litre bm s no problem . spec wise it has everything. Mine has the command system which I think is the only extra you can buy if you get chance to buy a second hand one buy it convert to lpg and you have the ultimate car with good true all round performance and beter economy than diesel.