View Single Post
  #3  
Old July 24th 05, 02:04 PM
Daniel J. Stern
external usenet poster
 
Posts: n/a
Default

On Sun, 24 Jul 2005, gary wrote:

> I thought the ratings were done on a flat road on the moon where there
> is 1/7th the gravity in order to get those MPG results.


The difficulty is in the stackup of assumptions and calculation margins.
The MPG protocol, believe it or don't, amounts more or less to "Let's see,
we measured *about* such-and-such percent HC and CO in the exhaust, and
the catalytic converter efficiency is *about* such-and-such percent, so we
can assume that *about* such-and-such amount of CO and HC is coming off
the manifold, which would mean that *about* such-and-such an amount of
fuel was burned".

Never mind that simply measuring the liquid volume of fuel before and
after the vehicle is run is considerably easier, more direct, more precise
and more accurate, that's not how it's done.
Ads