John - Yes, there are always exceptions to any general statement, but I have
not met anyone who, in what would be considered "normal" driving, did not
get at least 25 mpg in a M-B Diesel car. Usually, the claim is for much
higher numbers.
I keep pretty detailed records of fuel consumption for all my vehicles, and
over a period of years, my '90D 2.5 has averaged between 30 and 31 mpg; and
the '83SD has done between 27 and 29 mpg. That includes Interstate and
local driving, even some infrequent MBCA track time (which lowers the
average, but when you look at years, is just a ripple). Anyone who has ever
been with me will attest that I have a "heavy" foot, too.
If I were to see a sudden drop to 25 mpg or less, I would certainly start to
look for the reason!
Werner
----- Original Message -----
From: "John Robbins" <[EMAIL PROTECTED]>
To: "Mercedes Discussion List" <mercedes@okiebenz.com>
Sent: Tuesday, January 09, 2007 12:57 PM
Subject: Re: [MBZ] Diesel vs. gasoline
Werner Fehlauer wrote:
If any M-B Diesel car gets less than 25 mpg, there is probably something
wrong with the engine. Of course, it could be driving in 1st gear in the
city and idling a lot, but in normal use, I would do some serious looking
at
the engine!
I do not think you can make that blanket of a statement since driving
habits have a SIGNIFICANT effect on mileage. Diesels produce horsepower
with a direct relationship to injected fuel. So the more HP you use
the more fuel you use.
A point in case. I drive a 79 300SD, which is about ~4000lbs. I live
about 4 miles from campus. I also have a part time job, which is about
3 miles from home and 2.5 miles from campus. The vehicle doesn't reach
operating temperature until near the end of the trip, which also affects
fuel economy. There are at least two traffic lights involved in any of
the trips. I leave a traffic light or stop sign at full throttle >90%
of the time. I continue at full throttle (barring pedestrians, traffic,
etc) till about 10mph over (either 55mph or 40mph on the roads around
here, I try to stay below 25mph on campus). Throw in the occasional
trip to Wal-mart, which has a few 0-75mph in there.
Basically, every mile do a 0-60 run in your car. For an entire tank.
Personally, I think it is simply amazing that I get 20-21 mpg doing
this. Could you imagine what my mileage would be with a 3L gasser?
My driving habits may sound on the aggressive side (and they are), but a
milder version of this is entirely plausible for people living in large
cities (in Phoenix most people do 50-60mph on city streets and traffic
lights are ~1 mile apart).
I think saying that all Mercedes diesels should be able to *achieve*
25mpg is a very valid statement. Saying that something is mechanically
wrong if they aren't getting 25mpg isn't as much. Not trying to beat
you over or anything... just trying to very thoroughly make my point
(I'm an engineer, can't help it!!). :-)
