Mercedes-Benz E-Class 2009Change

I had my E300 for 4 years now and all I can say, it is an amazing car. I don't think it gets any better than driving this car on highway. I've been driving for many year, all kind of cars and makes but this is my first Mercedes and I am impressed.
I am thinking to sell it just to buy an newer E350.
On the other hand, it's a perfect car ... why change it ?
Hard to decide :)

I bought this car because my commute takes me abou 45 min. It is very nice relaxing in this car and listening to the Harmon/Kardon stereo. Plus with the fuel economy from the Diesel I only need to fill up every couple of weeks instead of every week in my other car. Also unlike other cars that get good economy this one doesn't lack in power, it has 400 ftlb of torque!!! That will allow you to keep up with a good number of sports cars.

Plus with how good Mercedes is at building Diesel engines this one should be good for at least 500,000 KMS. I just passed 100,000 KMS, and the whole car still feels like new, and hasn't had a single problem.

This car is fantastic, smokes most cars off the line. Extreemly safe and comfortable. Top notch seats and interior, all the bells an whistles you could ever want. The only down side is limited traction with the std sports tires on cold and slipery roads. Best car I have ever owned.