winter fuel consumption

[Kunz, Bob]

Interesting a lot of people assume MTBE is pervasive in US gasoline, it is not. E10 is the norm. Both are in place to add oxygen content to fuel (originally) to reduce emissions. However, with current emissions systems in cars, neither is needed. E10 is there to satiate the ethanol producers. Your 200 would probably like E0 better. My '86 5Ks sure does.

Fuel is blended seasonally and this changes the vapor pressure which can lead to your symptom. At fuel cut off in open loop as you change gears the mixture will go lean giving a momentary RPM increase.

Fuel ecomonmy as others have pointed out is a simple thermodynamics issue. The engine has to produce more power to overcome the additional demand on it in winter driving. What percentage drop are you seeing? I wouldn't be looking for something wrong even up to 25%.

--bob


-----Original Message-----
From: quattro-bounces at audifans.com [mailto:quattro-bounces at audifans.com] On Behalf Of 200q 20v
Subject: winter fuel consumption

Every winter my 200 becomes a gas guzzler. With the coldest winter on
my ownership on record (global warming?) it has been the worst. It is
approaching consumption of a 4.2 V8  in city driving. There is no loss
of power, fuel smell, unusual exhaust, etc. VAG-COM data appears to be
withing recommended limits.

The only observation is that when engine is cold simultaneous clutch
disengagement/gas release while driving with no acceleration (2nd or
3rd gear) on a horizontal road results in noticeable RPM increase for
a fraction of a second. If accelerating it is even more noticeable.

Has anyone seen/solved anything like this?
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