I have driven a 1987 300E for 6.5 years, putting 21,000 miles on it.
Maintenance has averaged $923 per year (or a few monthly payments on a
new Honda). Although the car I bought with 187,000 miles on it had a
recent transmission, radiator, air conditioning compressor and blower
replacement; I have since replaced water pump (froze and burnt belt),
tires, forward muffler, brakes, speedometer, valve stem seals, injectors
and several air conditioning troubleshooting and recharge services.
Getting it to pass California smog requires a week or so in the shop
every two years.
I planned on budgeting $1,500 a year for maintenance when I took on an
older Mercedes, and have averaged about 2/3 of that. With the air
conditioning operating flawlessly for two seasons now and the valve
seals eliminating frequent spark plug changes, my maintenance costs
should be less now.
My maintenance has been rather high, but if you drive an older Mercedes
for a number of years, the maintenance averages out less than the
depreciation on a new car . . . and you are riding with style! You only
live once . . .