Working out miles per litre of petrol

Iceweasel

AdrianC wrote: »

No, they didn't. Look back up the thread a bit.

I haven't forgotten what was said earlier Adrian, but if a teacher was to use Imperial units after August 1970 that would have been a personal choice to do something additional, as it certainly wasn't in the approved syllabus.

There were no exams set in Imperial, or text-books with Imperial after 1970 approved for use.

I don't doubt you, but your experiences cannot be typical - certainly not in Scotland.

We had to endure countless in-service courses about changing over.

My wife at the time was a Primary School teacher and her school even had to have special meetings for parents who wanted to help their kids with homework, and were not teaching them the 'correct' way.

andrewf75

londonTiger wrote: »

mpg is useful because we only really use this metric to compare fuel efficiency between cars, we don't really need to know how much a gallon is. What we just need to know is that a landrover is x mpg and a volvo estate is y mpg therefore volvo is better becasue it has higher mpg and more efficient.

It's not like we have to visualise how many coke bottles are required to hold a gallon and also visualise how long 30 miles are if we were to stand on top of a small mountain looking over the horizon in order to understand the concept.

Thats a fair point, but in every single other country in the world, people are also able to easily make calculations such as how much fuel do I need to drive from A to B or how far can I go on x amount of fuel. We could do this a generation ago as well. This is the kind of thing that has been completely lost due to our confusion of different measurements.

The fact that mpg is only useful as a metric to compare between cars is directly because we don't use gallons any more, making it useless for anything else.

AdrianC

andrewf75 wrote: »

Thats a fair point, but in every single other country in the world, people are also able to easily make calculations such as how much fuel do I need to drive from A to B or how far can I go on x amount of fuel.

But, again, that's kinda irrelevant - since the majority of people don't buy "x amount" of fuel. They either fill their tank or they shove £y in.

Given that, surely the useful metrics are either tank range or p/mile.

andrewf75

AdrianC wrote: »

But, again, that's kinda irrelevant - since the majority of people don't buy "x amount" of fuel. They either fill their tank or they shove £y in.

The majority maybe, but for the rest its a pain - and I'd argue that if your fuel consumption units match those you actually use then the measurement is more meaningful even for the majority who don't really think about it in depth.

The reason most people don't think about it is probably largely because to get anything meaningful requires a calculator.

WTFH

My normal thinking when I get in the car:
How long is my journey?
What range have I left in the tank?
Is there a sensible & cheap fuel station on the journey (if necessary)?
Will I be going somewhere that has very cheap fuel in the near future? (if so, the next fill up should be enough to get me to cheap fuel.)

I know the average mpg of my car, but that serves no meaningful purpose in terms of journey planning. It's an average mpg, but if there's a traffic jam, or I'm driving in town a lot, the actual range I get will be less than if I'm sitting at a constant speed at or below the speed limit on a motorway.

WTFH

Or here's another way to think about it. Let's say you know your car does 50mpg. Good for you. Then to work out how much of a tank you are going to use, well, you'd need to know how many gallons were in the tank. How do you know that?
Well, you look at the gauge and then divide it down and get a rough idea - if the tank if 16 gallons and the needle is just under half full that means you've got a bit less than 8 gallons in it. Maybe. Or maybe not. Does the needle read true? So, if you've got 8 gallons left and you have a 350 mile journey ahead, then take 350, divide by 50 and you get 7, so you should have 4.54 litres of fuel left in your tank.

Alternatively, you get into the car, look at the tank range, see it is 400 miles, realise that is greater than 350, so you know it's OK. You check it again on your journey to make sure the number of miles in the tank is more than the distance.
No calculation necessary!

andrewf75

I'm not suggesting we really need to do these calculations every day. But I still don't think its healthy to have an ongoing situation where people can't do basic calculations with measurement. maybe a better example is something else e.g off the top of my head measuring the area of a room.

4.5m x 6.12m. Everyone over the age of about 12 can do it in half a minute (on a calculator since I've used non-round numbers)

How about 12 foot 4 x 8 foot 11? How many could do it now?

AdrianC

andrewf75 wrote: »

But I still don't think its healthy to have an ongoing situation where people can't do basic calculations with measurement.

TBF, many people are functionally innumerate.