Global versus US. Globally, transportation accounts for about 14%. Here in the US, about 29%.
Globally, all passenger cars and light duty trucks (pickups and SUVs), taken together, account for about 6%.
I don't have a specific source, but I think some of that difference stems from other countries still using substantial amounts of coal and oil in their electricity production. And while I can't agree with everything olskool has written, he's right about at least one thing. China, Russia, India and most other developing countries don't care. The argument many countries make is that they're trying to achieve the same quality of life that we in the west already have and they believe that having to massively curb their GHG emissions would hamper that. They don't consider it fair that we (the west) are trying to impose restrictions hampering their economic growth when all they're trying to do is catch up.
Now, India, while substantial emitters as a whole, are a fair way down the list on a per capita basis. Even China does way better on a per capita basis than we do in North America. And, while we've been cutting emissions on a per capita basis, China has been increasing substantially.
Here in Canada, we're similar to the US. Transportation accounts for ~25% of emissions. But the oil and gas sector accounts for another 26%. Some will point to that and say since we're producing oil that ultimately goes into cars to be used as fuel, that's 50% of our emissions. But that's not true, we export ~75% of the oil and gas we produce - something like 90% of that to the US. So only 6.5% of our total
could be additive towards our transportation numbers. But again, as someone else pointed out, That oil and gas is not used for
just transportation. Some of it goes towards heating, electricity generation, production of plastics and other petroleum based products. In the end, the total transportation GHG, doesn;t accumulate much more than that original 25% - may a few percentage points more. But still, 25% of something is still pretty substantial and worth addressing.
But again, a wholesale shift towards EVs is going to be difficult when the infrastructure isn't there to support it. And we're looking at 2035 to ban the sale of ICE passenger vehicles. No way we're going to double our generating capacity in 13 years. Going to take nearly that long just to get approvals from everyone.