Re: [DMCForum] Re: DeLorean MPG

[Martin Gutkowski <martin@xxxxxxxxxxxxxx>]

Now you guys know that Bill and I often don't see eye-to-eye, and on 
readig this e-mail, I jumped in and calculated my own MPG based on a 
surprisingly long trip in my own car. I remember the total cost of the 
fuel (a shade under £40), the cost per litre (81.9p) filling an almost 
dry tank to the brim, then driving from Newcastle to London without 
filling - approx 275 miles, and had probably 20 miles left in the tank 
on arrival. To cut a long story short, I thought the car did very well, 
better than it ever did with a lambda system and cat (both now binned). 
Using onlineconversion.com, and a calculator, this averaged out at just 
under 20mpg where the g is US liquid gallon. If I were to work it out in 
imperial gallons, well it drops to nearer 15!

I used 95 RON unleaded - which is our "regular" unleaded. Read below for 
explanation (quote)

The most important characteristic of petrol is its Research Octane 
Number (RON) or octane rating, which is a measure of how resistant 
petrol is to premature detonation (knocking). It is measured relative to 
a mixture of isooctane (2,2,4-trimethylpentane) and n-heptane. So an 
87-octane petrol has the same knock resistance as a mixture of 87% 
isooctane and 13% n-heptane.

There is another type of Octane, called "Motor Octane Number" (MON), 
which is a better measure of how the fuel behaves when under load. Its 
definition is also based on the mixture of isooctane and n-heptane that 
has the same performance. Depending on the composition of the fuel, the 
MON of a modern petrol will be about 10 points lower than the RON. 
Normally fuel specifications require both a minimum RON and a minimum MON.

In most countries (including all of Europe and Australia) the 'headline' 
octane that would be shown on the pump is the RON: but in the United 
States and some other countries the headline number is the average of 
the RON and the MON, sometimes called the "roaD Octane Number" or DON, 
or (R+M)/2. Because of the 10 point difference noted above this means 
that the octane in the United States will be about 5 points lower than 
the same fuel elsewhere: 87 octane fuel, the "normal" petrol in the US 
and Canada, would be 92 in Europe.

Martin

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