Cars: Energy and Carbon Performance

This page includes a series of tables designed to help compare the energy and carbon performance of a range of petrol, diesel and electric cars. Including the performance of electric cars at different levels of grid de-carbonisation and overall performance including the embodied energy used in manufacturing the lithium ion batteries.

Petrol cars

4.54609 Litres in a gallon, 9.7 kWh in a Litre, 2.31 kg CO2 per Litre

MPG MPL Miles/kWh gCO2/mile gCO2/km
80 17.6 1.81 131 82
75 16.5 1.70 140 87
70 15.4 1.59 150 93
65 14.3 1.47 162 100
60 13.2 1.36 175 109
55 12.1 1.25 191 119
50 11.0 1.13 210 130
45 9.9 1.02 233 145
40 8.8 0.91 263 163
35 7.7 0.79 300 186
30 6.6 0.68 350 217
25 5.5 0.57 420 261
20 4.4 0.45 525 326
15 3.3 0.34 700 435
10 2.2 0.23 1050 652

Diesel cars

4.54609 Litres in a gallon, 10.7 kWh in a Litre, 2.68 kg CO2 per Litre

MPG MPL Miles/kWh gCO2/mile gCO2/km
80 17.6 1.64 152 95
75 16.5 1.54 162 101
70 15.4 1.44 174 108
65 14.3 1.34 187 116
60 13.2 1.23 203 126
55 12.1 1.13 222 138
50 11.0 1.03 244 151
45 9.9 0.93 271 168
40 8.8 0.82 305 189
35 7.7 0.72 348 216
30 6.6 0.62 406 252
25 5.5 0.51 487 303
20 4.4 0.41 609 378
15 3.3 0.31 812 504
10 2.2 0.21 1218 757

Electric vehicles

Electric cars are often quoted at a performance of 4 miles/kWh which can easily be achieved with electric cars such as the Nissan Leaf and Renault Zoe. This performance is dependent on acceleration, de-acceleration, speed and terrain in the same way as internal combustion cars.

Grid electric @ 500 gCO2/kWh

miles/kWh gCO2/mile gCO2/km
4.4 114 71
4.2 119 74
4 125 78
3.8 132 82
3.6 139 86
3.4 147 91
3.2 156 97

Grid electric @ 400 gCO2/kWh

miles/kWh gCO2/mile gCO2/km
4.4 91 56
4.2 95 59
4 100 62
3.8 105 65
3.6 111 69
3.4 118 73
3.2 125 78

Grid electric @ 367 gCO2/kWh (UK 2015 grid average intensity ~ Gas CCGT intensity)

miles/kWh gCO2/mile gCO2/km
4.4 83 52
4.2 87 54
4 92 57
3.8 97 60
3.6 102 63
3.4 108 67
3.2 115 71

Grid electric @ 300 gCO2/kWh

miles/kWh gCO2/mile gCO2/km
4.4 68 42
4.2 71 44
4 75 47
3.8 79 49
3.6 83 52
3.4 88 55
3.2 94 58

Grid electric @ 200 gCO2/kWh

miles/kWh gCO2/mile gCO2/km
4.4 45 28
4.2 48 30
4 50 31
3.8 53 33
3.6 56 35
3.4 59 37
3.2 63 39

Grid electric @ 100 gCO2/kWh

miles/kWh gCO2/mile gCO2/km
4.4 25 16
4.2 26 16
4 28 17
3.8 29 18
3.6 31 19
3.4 32 20
3.2 34 21

Grid electric @ 0 gCO2/kWh

miles/kWh gCO2/mile gCO2/km
4.4 0 0
4.2 0 0
4 0 0
3.8 0 0
3.6 0 0
3.4 0 0
3.2 0 0

Taking into account lithium ion battery embodied energy

Figures for the embodied energy and carbon emissions of manufacturing often have fairly large error margins due to differences in manufacturing techniques and factors such as the fuel mix of the electricity used by a factory.

One of the more recent papers available that provides a guide to the embodied energy of lithium ion batteries among other technologies is a paper published in 2015 in the royal society of chemistry on Hydrogen or batteries for grid storage? A net energy analysis. The figure quoted suggests that each kWh of lithium ion battery requires 136 kWh of energy to manufacture. An earlier paper published by members of the same team suggested an embodied energy of 454 kWh per kWh (figure 1).

Using 136 kWh per kWh of battery and a battery capacity of 24 kWh for the Nissan Leaf requiring a total of 3264 kWh to manufacture and assuming 120k miles over the lifetime of the car (Some Nissan Leafs have passed 170k miles with appox 26% reduction in capacity.

120,000 miles @ 4.0 miles/kWh: 30,000 kWh
Adding the manufacturing energy of 3264 kWh
Total energy demand: 33,264 kWh
Total performance: 3.61 miles/kWh

A Nissan leaf driven normally in a relatively hilly rural area (Snowdonia North Wales) with a fair amount of acceleration & de-acceleration in our own testing achieves about 3.8 miles/kWh (over 4 miles/Kwh is easily achievable on flat roads at moderate speed). Including the embodied energy of the battery would drop this to 3.44 miles/kWh. At the UK average grid intensity of 367gCO2/kWh in 2015, this would equate to 107gCO2/mile or 67gCO2/km. Which would provide a carbon savings of 28% compared to a 70 MPG petrol car, 39% compared to 60 MPG and 48% compared to 50 MPG.

If the embodied energy of the battery is not included as the carbon impact of battery manufacturing is more complicated and depends on many other factors the savings would be 36%, 45% and 54% respectively. It's also worth noting that lithium batteries can at the end of they useful life in a car be put to good use as grid storage then eventually recycled.

These savings will only improve as the grid further de-carbonises and will be larger if the electric car is charging from home solar or a other renewable source. There is some debate as to the emission factor claimable from green tariff electricity in the UK as part of the subsidy for renewable generation is paid for by all electricity customers. A more detailed discussion on this topic can be found here. In order to provide a middle road between claiming zero emissions and grid average carbon intensity, we calculated a rough estimate of an emission factor based on who pays for the ROC's subsidy in the UK (detailed here) which worked out to be of 218 gCO2/kWh. At this emission factor an electric car without the battery emissions included would save 62% vs 70MPG, 67% vs 60MPG, 73% vs 50MPG and with an estimate of battery emissions: 58% vs 70MPG, 64% vs 60MPG, 70% vs 60MPG.