after working on the V6 in the 05 E320 a little
 

I'll say that I am somewhat impressed with what I have seen so far. In addition, everything I'm reading seems to indicate that these are pretty robust engines. It is a pleasure driving/riding in the 05 E320 wagon:).

Yeah, I'll second that opinion. I've got two M112 powered MB's and they both purr. My 203 just turned 100K and the Mrs. 210 has 75K. We've had them both for a few years and other than regular maintenance the only thing they've needed were valve cover gaskets and CKP sensors. Stick with premium fuel and use Techron once or twice a year and you're good to go.

Other than that, the only thing to keep a close eye on would be the oil pressure test fitting. Replace the rubber gasket at the first sign of leakage. The part is only a few bucks and it's simple to change. :)

I'll third the opinion.

I bought a new CLK320 in 1998 and sold it to a friend at 50K miles, he in turn sold it to another mutual friend who has now had it for over 10 years. I ran into him the other day and the car now has 304K miles on the clock.

The engine still runs as new and has only had valve cover gaskets, plug wires belts and the recommended oils changes at 10-12K intervals. Doesn't leak, drip or burn oil. Original water pump and alternator, the A/C compressor was changed a couple of years ago. 722.6 transmission has the same fluid and filter that were installed in Germany in 1997.

We're constantly hearing about how unreliable the newer cars are or the ever popular 'they just don't build em like my old 240D..... ' stories but from where I'm sitting some of the newer cars have long-term reliability that the older cars could only dream about.

Flame suit on.

The M112/M113 engines ARE the most reliable MB gas engines!
At least in my humble opinion.

My dad's M116 in his 420 is original other than the valve guides/seals and a timing chain, still runs great at 305k+ Its all about maintenance.

I alllmost bought an E320 wagon recently but decided not to due to their fuel consumption and complexity. Ended up with a '13 TDI sportwagen 6-speed. Awesome vehicle. If MB would release a diesel C-class or E-class wagon here I'd have likely gone that route. The W203 C220 cdi we had in germany on a trip was awesome...too bad its not sold here. :(