I'm not sure that point revolves around the manufacturing of the car and bikes, even though that should be included.

There was a study, that sadly eludes me, that suggested that if you need to travel more than 2km to do you grocery shopping, then it would produce less CO2 to get in your car and drive, compared to walking.

The reasoning is that you need to consume some amount of food to generate the energy required to walk to the store and back. The amount of CO2 used to generate that food, and the additional CO2 you exhale, would be larger than what a modern car would produce, traveling the same distance.

I believe that the same argument that would make multiple people in an EV carpool more environmentally friendly than bikes. But that's also the case with regular cars.

> Wouldn’t there be more CO2 involved in producing the car compared to a few bikes?

Crazily enough there's generally less CO2 involved in producing the car than having each of a few people ride bicycles a distance equal to a typical car's life-cycle mileage.

Here's my math: For lack of a better source I'm using Renault's own environmental assessment for the Fluence Z.E[0], which puts its production-related emissions at ~8 metric tonnes of CO2. Over 150k km (which is not a lot for a car, but we want a number achievable by a cyclist over their lifetime) that results in ~53.3g/km of CO2.

As for driving let's assume that a fully loaded EV requires 200Wh/km to move around - In France that amounts to 10.6g/km[1].

So overall we have a well-to-wheels footprint of 63.9g/km.

Now here's the fun part:

A typical Vegan will be responsible for 1.5 metric tonnes of CO2 annualy @ 2600kcal daily, so 1kcal = ~1.57g of CO2 - This is the most environmentally friendly diet. Cycling can vary greatly in intensity[3], but let's say 250kcal/h at 10km/h is a reasonable estimate.

Given these figures a single vegan on a bicycle going 10km/h is responsible for 39.25g/km of CO2. According to some sources[4] my numbers aren't that far off.

CONCLUSION (caps for visibility): Two vegans on bicycles having a 17km commute are responsible for 78.5g/km, while the same two vegans in an EV in France produce only 63.9g/km. Bump that to four vegans and we're getting awkwardly close to a typical combustion engine car's emissions.

Meanwhile environmentally conscious(heh) meat-eaters should probably stay off bicycles, eat less and carpool in a compact car.

[0] Page 91 of: https://group.renault.com/wp-content/uploads/2014/09/fluence...

[1] http://environmentalprogress.org/big-news/2017/2/11/german-e...

[2] http://www.greeneatz.com/foods-carbon-footprint.html

[3] https://keisan.casio.com/exec/system/1350958587

[4] https://www.theguardian.com/environment/2010/jun/08/carbon-f...

EDIT: formatting.

While I whole heatedly applaud your efforts; reducing this down to carbon emissions alone is so completely ridiculous as far as logical arguments go.

There are a whole host of negative externalities involved in driving a car that riding a bike (or 4) just don't even come close to.

You're absolutely right and I wouldn't suggest anybody to ditch their bike in favor of a car just because one factor supports this notion.

But this exercise shows one thing: when it comes to reducing our carbon footprint personal transport is actually a relatively low hanging fruit. Same for electricity really.

Food seems to be the hard problem here. I heard somewhere that a safe level of emissions is one metric tonne of CO2 per capita annually. Vegans do 1.5t.

Maybe it will get lower once transportation is cleaned up? I don't know.

EDIT: To be clear - my original write-up was a little bit in jest. This one is my serious position.

This is orthogonal to your point, but: people usually limit their commute by bike to, say, less than 5 to 10 km one way. On the other hand, people think nothing of commuting 50 to 100 km one way by car.