Sir:

There can be no reasonable comparison between 1960's era 2T's and the modern computer-controlled engines of this era.

Suffice to say the 2T's were not even economical for their era, but in their defence I would say that they were NEVER intended to be so, they were performance engines.

Toyota's economical engines of the same period were the 3K series, and that old design, albeit highly modified, is still around with us today - 4K, 5K engines.

The difference between the old 3K and the newer 4K and 5K is the STROKE, these engines made the transition from over-square designs to under-square designs, where the stroke became larger than the bore.

The reason they did this was that it has been discovered, by hard experience that long-stoke (under square) engines are more efficient than short-stroke (over square) engines.

If you add better mechanicals of the modern engines to electronic fuel injection and electronic ignition, (total engine management) then all modern engines are much more economical than their old counterparts.

The only real drawback of the modern engines and vehicles is COST - spare parts are more expensive, and they are harder to maintain and tune unless you have the proper training and equipment.

Best Regards,

Dusky Lim