Matt M.

# Mpg to l/100km conversion, fuel economy problem?

We have two vehicles
A:old truck that does 17 mpg (13.84l/100km)
and
B:old car that does 47 mpg (5.00l/100km)
We are looking to replace one of these vehicles with a new one (of the same size)
C: new truck 19 mpg (12.38l/100km)
or
D: new car 61 mpg (3.85l/100km)

So which vehicle should we replace to save fuel? The old truck or the old car to end up with.
2). BC (new truck+old car)

The way I solved this:
A:Old truck 13.84l/100km + D:new car 3.85l/100km = 17.69l/100km,
B:New truck 12.38l/100km + C:old car 5.00/100km = 17.39l/100km
Combination BC uses less fuel.(0.31l less)

Now using mpg:
17mpg+61mpg=78mpg
19mpg+47mpg=66mpg
Making the combination AD a better choice.

Why the exact opposite answer? What am I missing here?

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Matt M.

So if the question is what combination of vehicles saves us more fuel? What is the answer? Or is the question wrong in the first place? If so what wold the right question be?
Report

02/08/16

Amanda R.

Since you want fuel economy you would want to compare numbers that show the fuel usages to get the most direct answer.  You could also convert the mpg values to gallons per mile.
Report

02/09/16

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