[W126 Coupe] Economy gauge: 1990 560 SEC

[FPecar4525 at aol.com]

In a message dated 10/2/2009 5:49:18 P.M. Pacific Daylight Time,  
rkhallberg at mindspring.com writes:

Lou,

Based on how the "Economy" gauge on my 91 560 SEC  behaves, I believe it 
is simply a manifold vacuum gauge.  If my  assumption is correct, the 
correlation with fuel economy is very crude and  basically yields very 
little past a bit of cockpit entertainment.   These cars, I think, 
predate accurate/inexpensive fuel flowmeters used in  many of current 
vehicles to furnish data for the calculation and display  of true fuel 
economy.

Running in 3rd gear, I think, would keep the  engine in a sweeter spot of 
the power curve, but would probably average  out to be considerably less 
economical than running in 4th gear and  letting the transmission decide 
when a downshift is needed.  These  cars are designed for autobahn use 
and tend to be a bit sluggish below  somewhere around 80, at which point 
they come alive and perform  effortlessly.  My opinion is that they 
primarily should be enjoyed,  so, when in the hills, drive it in 3rd if 
it makes you and the car feel  better.

Party On!

Richard


I agree with Richard.  In the "old"  days I remember other 
"efficiency/economy" gauges on other vehicles which were  merely measurements of vacuum at 
the manifold.  At the time, they were a  new way of expressing efficiency but 
once microcomputers began to be introduced  into the automotive world, went 
the way of "high button shoes and buggy  whips".  That said, I love looking 
at that gauge on my '89 560SEC and yes,  sometimes I actually alter my 
acceleration pattern based on what it tells  me.
 
Frank Pecarich
 
Frank Pecarich
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