Yes, modern engines are optimised for fuel and emissions efficiency to within an inch of their lives. This was my entire point - we could move a couple of people in a Fiat 500 and get 43mpg, in 1957. Without the incentives I mentioned in my first post, we could easily make an engine much more efficient than that, and fixable.
As you ignored my comment on our other discussion, and continue the conversation here - I also assume you have electric heating and hot water at your house. After all, everyone needs to do everything possible to reduce fossil fuel usage, right?