Okay, Twitter, I've been looking at how car emissions are related to vehicle weight. We all know there must be a relationship, but I thought I'd see exactly how it looked. Can you check my working?
THREAD 1/10
THREAD 1/10
I grabbed information from Parker's car guide, only using vehicles where the emissions scores used the newer WLTP test protocol, which should more closely mirror real driving.
The cars I included were a semi-random range of those on the UK roads.
2/10
The cars I included were a semi-random range of those on the UK roads.
2/10
(Turns out there's a wild number of sub-models for many of the cars on sale, so I always took the first that was listed, which I *think* always gave me the base model)
3/10
3/10
For each car, I noted the specified weight and CO2 emissions and, well, here's a graph of what we get...
4/10
4/10
The relationship is modelled thus:
CO2 = -23.20 + 0.118 x weight, R-squared = .73
In other words, each extra kg on a car is fairly clearly associated with an average increase of 0.12 grammes of CO2 for each kilometre it is driven
* Add a tonne, emit 120g more each km *
5/10
CO2 = -23.20 + 0.118 x weight, R-squared = .73
In other words, each extra kg on a car is fairly clearly associated with an average increase of 0.12 grammes of CO2 for each kilometre it is driven
* Add a tonne, emit 120g more each km *
5/10
A few more informal observations.
First, Ford are really shameless at putting terms like "Eco" into the names of their models. Honestly, guys, you're fooling nobody #greenwashing
6/10
First, Ford are really shameless at putting terms like "Eco" into the names of their models. Honestly, guys, you're fooling nobody #greenwashing
6/10
Second, the very worst offenders are basically what you'd expect: the monumentally crass BMW X6 is 2320 kg but 300 gCO2/km and the Mercedes G Class is 2489 kp and 281 gCO2/km, even without Indiana Jones hanging off the front
7/10
7/10
That green dot right up at the top? Range Rover.
8/10
8/10
The source I used didn't include pickup trucks, disappointingly, but I see no reason why the relationship wouldn't hold - there are several popular vans in these data already
9/10
9/10
So in conclusion, we have to acknowledge that any given car trip can be accomplished with very different levels of pollution, and people can STRONGLY control this by not buying a heavy car
* These were ICEs, but this issue does not magically vanish with electric cars *
10/10
* These were ICEs, but this issue does not magically vanish with electric cars *
10/10
UPDATE: Somebody requested I add a few of the very smallest, lightest cars e.g., Toyota Aygo. Notably these <1 tonne cars tend to sit above the line, so are more polluting than their mass alone would suggest
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