I'll second this bug report. I was just about to make the same comment and found this thread, so I'll add what I found.
I noticed it while browsing vehicles, looking at the VW Touareg. Here it is
with no filters applied.
And here, looking at
Diesel V6 (147).
And here, looking at
Gas V8 (19).
The data below the graph seems to update, but sometimes it seems not to - for example, the avg for 2014 is 24.9mpg when unfiltered, or when filtered
this way. Not impossible, but seems unlikely. I'm guessing that this was just a coincidence, and that the data below the graph is Ok. But you might want to double-check it after looking at the graph.
But the kicker is, the graph itself never changes. Perhaps it's not meant to, but I expected it do, and it didn't.
Screenshots attached, but this links are probably easier to use.