[happiness_idx]

While the raw numbers might suggest that the heat from cars is negligible compared to solar radiation, that overlooks the Urban Heat Island (UHI) effect and the synergistic feedback loops that make urban areas hotter. The UHI effect shows that cities are warmer than their rural surroundings because of concentrated heat sources like cars, buildings, and human activities. This local heat really impacts urban microclimates.

Plus, the heat from cars creates feedback loops. More heat means more use of air conditioning, which releases even more heat exhaust, making the area even hotter. This cycle just keeps adding to the overall heat load in the city. So, even if the direct heat from cars seems minor on its own, it actually plays a significant role in making urban areas warmer.

[ch4s3]

The UHI effect is mostly down to solar radiation and the thermal mass of the built environment. The sun heats the concrete during the day which radiates heat at night, so that the next day the baseline is higher than the surrounding area. Cars and human activities are a drop in the bucket as a previous poster shows.

[anamexis]

I'm skeptical of that as well. It's my understanding that the Urban Heat Island effect is from roads and structures lowering albedo and absorbing more solar energy.

https://www.epa.gov/heatislands

https://www.heat.gov/pages/urban-heat-islands

https://www.annualreviews.org/content/journals/10.1146/annur...

A few of these do mention waste energy, but it seems to be a relatively small factor. And of waste energy, I would imagine that cars are themselves a somewhat small factor, compared to electric and natural gas usage.