[bluGill]

For ICE we are chasing the final 0.1% improvements. There are a few of them left, but each round eliminates more from the future things to find. Even if they all work out, total we are looking at most a couple percent improvement.

The same applies (maybe worse) to electric motors, but the efficiency of electric motors is substantially better.

there is a fair amount of work yet to be done with Batteries, but even there we know theoretical limits and are closing in on them. (Ask a chemist what they are). if you want to make a contribution to cars battery technology is currently where there is the most room for a big improvement.

Note, I have no idea what the costs for any of the above is. It maybe that ICE investments are still more cost effective. I doubt it, but I don't know. Not matter what improvements will be expensive.

[deutschewelle]

80% is the theoretical limit and we are struggling to get past 30% but I forsee dramatic economic incentives to increase this a lot higher. Doing so might raise costs of production however

[rootusrootus]

80% is the theoretical limit for what? AFAIK the theoretical limit for an Otto cycle engine is somewhere around 46%, and we're getting pretty close already.