Performance was paramount.
There’s really no need for the crazy top speeds modern cars a capable of.
If I could I would happily buy a new MK1 Golf, that’s all I really need for personal transport
(I use a van for work however)
An ultra eco diesel could be an option with ad blue & DPF etc.
But we only need around 1500cc displacement and that’s generous.
A smaller engine has to work harder to maintain a higher speed. That's why, as a general rule, larger engines are more economical on extended long drives at higher speed even when you take gearing out of the mix. A larger engine with higher performance can extract more energy per engine rotation and therefore more energy per time.
Please can you explain why 1500cc displace is the only thing we need? There are different horses for different courses.