sitting up ?
 

My question is, are there any special considerations regarding a well maintained garaged 1990 Diesel Mercedes with 180,000 miles, that is driven 100 miles over 2 days every 2 weeks? I disconnect the battery when garaged and always run the AC compressor awhile whenever I drive it.

Way overkill to disconnect the battery if sitting for a couple weeks, the only things using power in that car when its off is the clock and radio memory. :D

Its good to run the A/C compressor occasionally, my 420SEL is parked/asleep about 5 months of the year and I only run it for about 10 mins maybe twice during that time, and its been just fine, A/C still works great. And the diesels are even less affected by sitting than the gassers....my dad lets his 300SD sit all winter untouched, charged the battery this spring, turned the key, up and running just like it was turned off yesterday.