Hi Ben, any update on your car purchase? Did you go for a CL55?
I have owned mine for 3 years and done over 50k miles in that time and it's absolutely fantastic! The silly grin every time I drive it is hard to explain
As has been previously mentioned look at a good few to understand them, what the different options are, what is important to you and buy the best you can afford, age, mileage, fsh, spec etc etc and if need be get an 'indy' to check it over and give you some unbiased advice.
If bought and maintained correctly they are magnificent cars - quick, comfortable & stylish (IMHO).
And the forum is full of Merc guru's so anything you need to know/ask will be on here somewhere.
I did get quite 'anorak-y' about it - did the total tank/miles thing a few times and checked my usual 34 mile each way commute & it was pretty accurate.....certainly within 5%. Now I've thrown the anorak away and bought an E63, so will never mention those three letters together again.
I agree I'm not too sure why people are looking at what are old amg's and hoping for good mpg. I mean these are 5.5 litre v8s some with superchargers. If you want power and economy get a 3.0 diesel.