I can't comment on MB warranties, but when I bought my '92 Aerostar from a Ford dealer in 1996, it had 56K on it, and seemed to be in great shape. It had passed a 126 point pre-sale used car inspection, and I wouldn't have bought the warranty. Fortunately for me, my credit union insisted. The warranty I got was a bumper-to-bumper that covered everything except the exhaust system and "sacrificial" parts like brake pads. I spent $1200 for 3-yr, 36,000 mile coverage. In those 3 yrs, the dealer made close to $6k in repairs to the Aerostar, including replacing a cylinder head.
If you can get an extended warranty on a car with 100K miles, depending upon the cost, coverage, and period covered, I'd grab it. I won't buy another nearly new car without one.
"We drive into the future using only our rearview mirror."
- Marshall McLuhan -
Northern California Wine Country...
"Turbos whistle, grapes wine..."