These guys are well worth the watch. They do some super cool stuff.
Or if you want to skip the video (2hrs Idle Time):
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Weird that the Mazda used half what the Subaru did. The Mazda used 60% of what my 4.8L v8 reports and the Subaru used 17% more than my truck.
However, they probably used a significant amount of gas pulling away from the pump and then back over to it compared to just idling. I guess this wasn't supposed to be exact though, just to give you a rough idea.