My 1974 Dasher had the upshift light. 

Karl Wolz
Sent from my electronic umbilicus

On Apr 18, 2012, at 5:06 PM, Kent Christensen <lkchris@OSOGRANDE.COM> wrote:

> Re:  Given the anomalies with the reported 65 mph data ...
> 
> 
> Some may recall in the 1980s that VW Golfs (and others) had an "upshift
> light" on the dash. (Maybe it was the '70s in which case it was "Rabbit.")
> A prod to do just that and useful for at least two reasons:
> 
> 1.  An engine running twice the rpms as another is very nearly equivalent to
> a twice as large engine running the same speed as the smaller engine.  Since
> gasoline engines mostly run near stoichiometric fuel/air ratio, it's nearly
> a direct relationship with fuel consumption increasing with engine speed, as
> the wider throttle opening permits consumption of more fuel/air mixture.
> 
> 2.  AND ... any throttled engine consumes power just running itself by
> virtue of the effort required to "suck" air past a partially closed
> throttle.  Called pumping loss.  The upshift at low rpms usually results in
> a wider open throttle condition, also increasing fuel economy.
> 
> Lots of interesting contrasts here with a diesel engine as they change
> speeds not by increasing air/fuel quantity but rather by simply burning more
> fuel to the same amount of air---yes, diesels don't have throttles and
> concurrently don't suffer pumping losses as a result.  At whichever speed a
> gasoline engine is running the fuel/air ratio is nearly always near 15 air/1
> fuel, while a diesel could run at idle at near 150 air to 1 fuel  (helping
> explain why an idling diesel cools down).
> 
> And, indeed greater speed equals greater drag, but at the same speed the
> gasoline engine running at lower rpm (higher gear) quite obviously burns
> less fuel.
> 
> Kent Christensen
> Albuquerque
> '81 Vanagon (owned since '83)
> and '07 Merc GL320CDI and '08 BMW R1200RT, '02 BMW R1100S, '84 BMW R80G/S