[Vwdiesel] Why gasss cars mpg sucks

[LBaird119 at aol.com]

In a message dated 5/11/2005 1:30:43 PM Pacific Standard Time, 
MarkRShirley at eaton.com writes:

> Hills will cost you energy to go up, but when you
> >go back (coast) down, you save fuel (no throttle plate and your
> > fuel injection shuts itself off, at least in TDI it does!).


  Not quite.  It never shuts off, it drops to idle volume but the rpm 
is high unless you drop into neutral.  So you're at minimum fueling 
but at higher rpms.  It's injecting fuel at every power stroke the 
engine turns over.

> >
> >If you end up at the same altitude at the end of your trip, it
> >(weight) should not make a HUGE difference in MPGs... right? 
> 

  Simple way to test a thought or theory is to take it to the extremes. 
Imagine the fuel/power/etc it takes to roll a moped, Honda 600, Mini, 
Rabbit, et al down the road and compare that to rolling a boxcar, semi
tractor/trailer etc down the road.  The coefficient of friction (rolling 
resistance) is higher for the higher weight.  Sure Newtons laws pertain 
about staying in motion but it's not in a vacuum, there's gravity so there 
are several outside forces acting on it.  Weight DOES matter and it 
CAN matter a lot.  Just like tire pressures can.
    Loren