Dan
I have the model that preceded this (I bought mine about 5 years ago).
CAN & OBD II Professional Scan Tool
It can read live data which is handy diagnosing running issues as it allows you to read what the 02 sensors are doing.
If you like the W210, consider the E420. They only made them for model year 1997. That year had the quad cam 32v M119 engine making 275hp but still getting a solid 20mpg mixed driving and 25mpg on the highway. I've had mine for about 10 years and 130k miles and it's been very reliable.
I like it more then my 02 E55
