[erik]

Your comment sent me down a bit of a rabbit hole. I was confused about how burning 1L of fuel, which weighs ~1kg, could possibly produce ~2.3kg of CO2.

(This page confirms Toyota's number: http://www.eia.gov/tools/faqs/faq.cfm?id=307&t=11 )

The answer, which took me far too long to realize, is that the oxygen pulled from the air makes up the bulk of the mass of the CO2. Oxygen has an atomic mass of ~16 to Carbon's ~12, which means that 1kg of pure carbon can be combined with oxygen to produce ~3.7kg of CO2.

So yes, your calculations sound about right. Contrary to my first impression they do not violate the law of conservation of mass.

[andrewwhartion]

Yeah, I did a double take when I saw the number as well, then realized there's an O2 in CO2..