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by arcticbull 1293 days ago
> There’s a profound amount of environmental impact beyond the gas pump, and most of it comes from building and shipping all the parts to assemble the automobile over and over again. The manufacturing process is profoundly environmentally destructive, so vehicles that have a longer service life (Land Cruiser is 2-2.5 times the average) have a role to play.

This isn't really true. The manufacturing is intensive but not nearly as intensive as setting fire to 1/4 gallon of gas every mile.

This impact is also significantly lower for gas cars than electric, which achieve parity around 15,000 driven miles.

There is an obvious inherent trade-off of a longer service life: you don't get efficiency improvements for 25 years.

[edit] Studies show an average gas car produces about 5.6t of CO2e in manufacture, an electric car about 8.8t of CO2e. For the gasoline car that's equivalent to burning ~600 gallons of gasoline and for the electric, ~1000 gallons.

An average car is driven 12500mi per year, and look if you're getting 10mpg, that's 6 months. How about the other 24 years 6 months? Buying a car that's 10% more efficient breaks even after what, a couple of years? [1]

If you care about the environment, take a train. Caltrain gets 100 passenger-miles per gallon average on their diesel engines and those train cars are older than I am. Once they move to electric, it should be 250-ish pax-mi/gal-equivalent based on Bart. Although I suspect probably a lot more due to the longer runs between stations.

[1] https://www.epa.gov/automotive-trends/highlights-automotive-...

1 comments

Regarding trains, I don't think that's really accurate. Yes, a train that's completely full gets excellent effective mileage per passenger for that trip. But how often are they anywhere near full? In reality, trains and buses have to make a huge number of runs either completely or virtually empty in order to have a regular enough schedule for anybody to be willing to depend on them. We need to know the effective fuel consumption of all runs actually made per total actual passenger-miles transported over the course of at least a week, maybe more like a month.

And that's before we account for any additional trips needed for personnel movements, car and track servicing, and other such things.

Those numbers are from Bart and Caltrain's operating reports.

The Bart number may have been during peak only so fair point there, I can certainly look for the systemwide average. [1]

The Caltrain number is average over FY2016-2018, from their sustainability report page 5. [2] They completed roughly 436M passenger-miles per year, and consumed roughly 4.4M gallons of diesel. Clocks in around 100 passenger-miles per gallon. I'm sure its worse now with the COVID numbers. I think it's a fair ballpark point of comparison though, and you can consider the Bart number an upper limit.

You're of course right its a function of ridership. An average freight train gets over 400 miles per gallon per ton of cargo.

[1] https://www.bart.gov/sites/default/files/docs/GreenSheet.pdf

[2] https://www.caltrain.com/about-caltrain/sustainability

No, what matters is the marginal additional emissions of a passenger choosing to ride the train. An empty train is going from A-B regardless.