Would you want all data in a straight up conversion? Every mi becomes km and every gallon becomes L? Or did you want the graph to reflect the L/100km listing we added on profiles instead of MPG?
I would like to see everything in metric. Some of us Canadians are in such a mixed imperial/metric world, we like to see our MPG, but everything else in metric. When I look at my total miles driven that doesn't really mean anything, or when I see avg price per gallon, that doesn't mean anything to me... I enter all my data in metric so maybe my stats could be in metric too. Or maybe Basic stats could be divided in two the top half is imperial and the bottom half is metric?
FYI... this site is awesome... I've shared it with all my friends...