Well, here goes. High "octane" fuel gets its name from the 8-carbon chain that is, technically speaking, "octane", although to be sure there are higher and lowerer molecular weight hydrocarbons in the mix that is gasoline. So lets see that's 8 Carbons, and 18 hydrogens. Every octane molecule that is burned efficiently produces 8 CO2's and
1 C8H18 +34 O2 = 8 CO2 + 8 H20 + energy.
1 octane weighs (12 x

+ (18 x1) = 114 gm/mole
1 CO2 weighs 12 + (2 x 16) = 44 gm/mole x 8 = 352 gm/mole
But here is the thing. No new carbon is created or destroyed. The "weight" you speak of comes from the chemical reaction with oxygen. And you get, yes ENERGY.
But Al Gore and anyone who believes in man-made global warming as a result of CO2 as a greenhouse gas is just too lazy to read readily available science on the subject or just too politically motivated to hear any other answer than what big governments and environmentalists want you to believe.
CO2 is highly soluble in water. Especially cold water. Like cold water in the ocean, which, it turns out is the world's largest source of CO2. If the climate warms up, and the cold water warms up, then the CO2 come out of solution in the cold water (like a warm Coke fizzing) and the atmospheric CO2 goes up. Warming caused increased atmospheric CO2 levels, not vice versa.
Global warming is the 21st century version of the witch doctor sacrificing a virgin at the alter to keep the gods of the underworld from causing volcanos (or pick your natural disaster . . .) but in the end, it is just a sacrifice in which you surrender something of value (nowadays, money and political power) to some witch doctor types at the UN or in Washington DC or wherever you want to surrender your tax dollars to.
Next time you are outside, take a look at the really big, bright round ball up there in the sky. It is called "The Sun" if you look at the physics of the "energy" that is involved in climate change in order of magnitude, then here is a rough comparison. The energy contributed to heating the earth and affecting the climate is like your car driving down the expressway at 70 MPH. The contribution of CO2 as a greenhouse gas contributing to global warming is one lug nut on one rear wheel of the car.
The most abundant greenhouse gas is: water vapor! And CO2? It makes it greatest contribution to the greenhouse effect when there is absolutely no water vapor to be found in the air. Like for example, the arctic or antarctic winters. And in this case, yes there is "average" warming at the poles, but it is mainly in the winter months, and the difference is something like -42 degrees average versus -44 degrees average. Not too much to do with melting glaciers, I think
But hey, keep sending those tax dollars in. And let's all be proud of that great American witch doctor, Al Gore's, for his Nobel Prize. He's done right well for someone with a room-temperature IQ who flunked out of divinity school and got set up in politics by his daddy, "the Old Gray Fox", Albert Gore Sr., from TN. And lets pony up some extra $ for those carbon credits. And lets get behind all three candidates who seem to support the Kyoto Accords - that will siphon off billions of American dollars and exempt all those "emerging" nations, like China and India. And for goodness sake, let's not drill for oil here in North America where we have huge reserves. Or build any more refineries. Or nuclear power plants. Or any rational thing that will actually produce enough energy to supply America's energy needs.
Oh my god! Global warming!! We must do something now or we're all toast!!! Time to sacrifice a few more virgins before it gets really bad!!!!
Conservation, like charity, begins at home. Conserve. Recycle. Drive fuel efficient vehicles. Carpool. Yes!!! But trust the US and UN to tell us the right thing to do and to "legislate" to enact laws that impair our personal liberties and hamstring corporations just to keep global warming at bay -- and sacrifice the virgin dollars they are asking to do it? Absolute lunacy. Superstition on the primeval level. Global ignorance that makes people like Al Gore multimillionaires, helps drive gasoline to $4/gal and makes your tax burden what it is today.
Just my opinion, but it is a well read and thoroughly reasoned opinion, I assure you.