We just came back from a 4500 mile trip in our '97 CL500 with 142000 Miles. Carefully prepared doing all of the normal maintenance things. Had a problem with an upper control arm not being secured but no other problems. Car ran like the proud beast that it is. One thing jumped out however, after we left Seattle we never saw another Benz or German car again until So Cal! So you would be on your own to find even a mechanic that even works on Benzes. We kept track of every drop of gas, got 21.989 miles to the gallon at an average of $3.89 per gallon. We spent about $760 on gas but enjoyed every minute of the trip.
My advice to you, replace all belts, hoses, new coolant, new t'stat, new plugs, all vacuum lines, service transmission, have good tires. You know what has to be done to make this a memorable trip.
We are thinking of a cross country run in 2015!
Anziani
'95 E420 132K
'97 CL500 142K