Kg CO2 per litre

If you burn a litre of diesel this will produce 2.6391 kgs of carbon dioxide. Petrol has a lower carbon content and so produces 2.3035 kgs of CO2. The precise figures depend on the quality of the fuel. Since fuel weighs less than a kilogram per litre, it is interesting to see how the weight of emissions is multiplied by the addition of oxygen. The tables below show how the official test figures for CO2 emissions and combined MPG can be equated to see how individual vehicles perform in terms of CO2 per litre. Some cars appear to do better than the standard chemistry would suggest, whereas others do worse. So these figures show how inaccurate the testing mechanism can be, and how different engines skew the results. The official tests measure exhaust gases only and then calculate the fuel consumption.
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Top 10 CO2/litre petrol vans
Make	Model	Derivative	CO2 (kg)/litre	CO2 (gpkm)	Litre per 100km	MPG (combined)	List price
Volkswagen	Caddy	2.0 EcoFuel 109PS	2.24	157	7.01	40.3	£16,499
Volkswagen	Caddy Maxi Van	2.0 EcoFuel 109PS	2.24	157	7.01	40.3	£18,779
Fiat	Doblo Cargo New	1.4 16v Petrol Combi N1 Active Euro 5	2.33	163	6.99	40.4	£16,955
Ford	Fiesta van	1.25 Duratec 82PS	2.34	133	5.70	49.6	£13,101
Vauxhall	Corsavan	1.2 16v Twinport	2.34	124	5.30	53.3	£13,125
Fiat	Doblo Cargo New	1.4 16v Petrol	2.35	169	7.21	39.2	£14,163
Fiat	Fiorino Combi	1.4 8v Petrol 75	2.37	165	6.97	40.5	£12,459
Ford	Transit Panel	2.3 Petrol 145PS 350 LWB HR RWD	2.37	287	12.12	23.3	£27,775
Citroen	Nemo	1.4i 75 X	2.37	164	6.91	40.9	£11,601
Fiat	Fiorino Cargo	1.4 8v Petrol 75	2.37	164	6.91	40.9	£11,660
Bottom 10 CO2/litre petrol vans
Make	Model	Derivative	CO2 (kg)/litre	CO2 (gpkm)	Litre per 100km	MPG (combined)	List price
Ford	Transit Panel	2.3 Petrol 145PS 300 MWB HR RWD	2.39	293	12.28	23.0	£24,056
Ford	Transit Panel	2.3 Petrol 145PS 330 SWB LR RWD	2.38	284	11.92	23.7	£24,191
Citroen	Berlingo	1.6i 16V 625 LX 90bhp L1 panel van	2.37	195	8.21	34.4	£14,620
Citroen	Nemo	1.4i 75 X	2.37	164	6.91	40.9	£11,601
Fiat	Fiorino Cargo	1.4 8v Petrol 75	2.37	164	6.91	40.9	£11,660
Peugeot	Bipper	S 1.4 Petrol Van	2.37	164	6.91	40.9	£11,538
Ford	Transit Panel	2.3 Petrol 145PS 350 LWB HR RWD	2.37	287	12.12	23.3	£27,775
Fiat	Fiorino Combi	1.4 8v Petrol 75	2.37	165	6.97	40.5	£12,459
Fiat	Doblo Cargo New	1.4 16v Petrol	2.35	169	7.21	39.2	£14,163
Vauxhall	Corsavan	1.2 16v Twinport	2.34	124	5.30	53.3	£13,125