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Comment by noname120 | Hacker News Reader

If you can't charge an electric car, you shouldn't take a hybrid either, it's the same problem. If you only charge the battery when braking the overall CO2 footprint over the lifecycle of the car is higher than if you had a thermal vehicle.

The reason is a combination of markedly higher CO2-equivalent emissions for manufacturing (two motors instead of one + big battery), increased weight for the same reason which causes an increase in fuel consumption + elevated tire/brakes degradation + decommissioning of the car causes more emissions. And this doesn't include the other negative externalities such as the ecological impact of the additional metal and rare earth extraction.

Hybrid cars only make sense from a CO2 perspective if you charge them and drive exclusively on electricity inside cities, with only an occasional fuel refill before long distance trips.

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> only charge the battery when braking

No, good hybrid drivetrains charge the battery during normal driving not just breaking. It saves gas by avoiding the least efficient RPM ranges of the engine.

~80%(battery & conversion losses) of 35% fuel efficiency easily beats 100% of 10% fuel efficiency. Using a 200HP engine to creep around a flat parking lot or run the AC while waiting etc is simply inherently inefficient so they turn the engine off. As a bonus you get that quick EV acceleration without an oversized engine that’s rarely operating efficiently.

As to emissions from car manufacturing, don’t ignore emissions from gasoline manufacturing. People get these comparisons wildly wrong by only looking at tailpipe emissions and ignoring upstream extraction, refining, and transportation emissions over the 25+ lifetime of an average car.

You're confusing hybrids with plugin-hybrids. In either case, these cars are far more efficient than standard ICE cars even if you never plug them in (e.g. your garden variety older Prius doesn't support plug-in but is far more efficient than e.g. a Camry).

> Hybrid cars only make sense from a CO2 perspective if you charge them and drive exclusively on electricity inside cities, with only an occasional fuel refill before long distance trips.

For many people the local fiscal perspective outweighs the CO2 perspective. Hybrids are often financially speaking more interesting than thermal due to tax incentives.

> two motors instead of one + big battery ... elevated brakes degradation

You might be simplifying a bit too much here. The most successful hybrid powertrains are built from the ground up as hybrids and the "hybridized" parts actually replace ICE parts that aren't needed anymore. For example, the HSD system in a Toyota hybrid replaces the clutch, gearbox, starter and alternator, and the result is much more robust.

Also the brakes on a hybrid usually degrade slower, because of recuperation.

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