M-B diesels in the 123 chassis (1977 - 1985) (240D, 300D, 300D
Turbodiesel and 300TD (station wagon) are tough, durable and reliable
machines. Each has its advantages and should be sought according to YOUR
Your late interest in a diesel is to achieve fuel economy so know that
these old engines deliver MPG from mid 20s to high 20s, using diesel #2.
Biodiesel is available in Bio100 (100%) and Bio20 (20% bio, 80% diesel)
in some areas but doesn't achieve quite the mileage of diesel #2.
These old diesels require more maintenance than say, a Honda or Ford so
a DIY maintenance program IS part of the cost saving equation. If DIY
mechanic work isn't in your equation then the repair cost will overcome
the diesel's fuel cost saving. DIY includes oil and filter changes at 5K
miles, engine valve adjustments at 15K miles and (all) filter
replacement at 30K miles. The cars are not hard to work on but differ
somewhat from domestic cars so one ought to buy some manuals to do the
The 4 cylinder 240D (2.4L) is the most basic model and was sold in the
USA with 4 speed manual or automatic transmissions thru '82 MY. The 240D
engine's modest power favors a 4 speed manual transmission; the
automatic version is OK for local driving but too slow for freeway
acceleration, IMHO. If his commute is local or back roads with no long
hills a 240D is a good choice.
The 300D is basically a 240D with a fifth cylinder added to make a five
cylinder 3.0L engine that makes 77 HP in its non-turbo version and 120
HP in its Turbodiesel version (which started in '82 or '83 MY). These
cars have power windows, and automatic climate control systems, most
have M-B Tex leatherette upholstery; real leather was an option. The
Turbodiesel is clearly the preferable of the 300D as its 0 to 60
acceleration is in the 12 to 14 second area whereas the non-turbo motor
is in the 18 - 20 second area. (Most new cars' are in the 10 to 12
The station wagon is good but only if you need a station wagon.
These cars are now 20 to 25 years old and many have done a lot of miles.
Some will tell you that M-Bs run for 500K miles - and some do - the ones
that get their oil changed every 2K miles and have fastidious owners. A
poorly maintained MB will be scrap after 200K miles so a car's condition
is the ONLY criteria to believe. When you are serious about a diesel car
spend $100 or $150 to have an independent M-B shop check the motor's
compression for that will assure you that the car is worth the $$ or
that it's not and thereby you avoid a financial hole. These cars are NOT
cheap to have repaired, DIY may become necessary. Most parts are
available on line from various vendors, parts are not cheap but are
Finally, don't buy a rust bucket. Check behind the firewall mounted
battery, the fenders and spare tire well.