Yes but co2 isn’t everything. How much space it uses, which could be used to keep biodiversity high is also very important and actually the bigger factor in the question of human civilization surviving. We can deal with hotness, but we can’t deal with no insects
Because right now we don’t have that much excess energy… Therefore it’s just a waste of energy to use it, because it is way less efficient. AND on top of it an hydrogen car also needs a battery just a smaller one. So it has all the downsides without any upsides. The only upside is that you can recharge your car faster and it has some more range. But both those things don’t matter for the average consumer