I am sorry I've been inactive with this blog for a while. I am currently studying a few months in Spain, so I've been in the "metric" world. However I went back home last week for a few days, and realised something rather interesting ...
Anyone looking at a car advertisement would be able to notice that emissions are never given in imperial units. It's solely given in gram(me)s per kilometre (g/km).
Now we know that this presents a problem, if:
a) road signs are in miles
b) fuel consumption is in miles per gallon [or even L/100km]
for example you're driving in a car with emissions of 100 g/km, for a distance of 385 miles.. how much CO<2 will be emitted?
100g * (385*1.6)km = 61600 g (61.6 kg) . This is still an approximate figure, because I rounded down the conversion factor between miles and km.
now if the distance were in km, look at the accuracy and precision.
100 g/km for a distance of 620km (same distance), we get
100 * 620 = 62000 g (62 kg) of CO<2.
If people are so concerned about meeting emissions targets and the like, why not make it easier to accurately calculate ones emissions?
You could use ounces per mile of CO<2, to be in accordance with the current system of miles on the road, but of course ounces are impossible to work with for anything that is scientific.
Hence the best solution to this would be to implement metric distance signs, and do something useful with the signs in miles, like recycle them as paperclips.