Stop global warming
Yes, I think we can. The present internal combustion engine was mostly developed in a time when fuel cost and efficiency were not imperatives. We need to go back to the early days of engine devleopment and reassess the way designers handled branches in the design road. We may have overlooked some better choices way back when the discovery of oil in Oklahoma and Texas seemed to say that there would be cheap gasoline forever.
One of these early branches in the road was a choice between four-stroke cycle engines and two-stroke cycle engines for automobiles. At the time, we used carburetors to feed fuel to the cylinders. In this context, the four-stroke engine is a far better choice. (More efficient and less polluting.)
But, the trend today is toward injection of fuel directly into the cylinders. With this modern option, the two-stroke cycle actually provides a far more efficient engine. Here are some other choices that need to be reviewed:
1. Engines are only designed for either gasoline or diesel, and nothing else.
2. Compression ratios are lower than one would choose for best efficiency.
3. Engine design principles are not based on a need to reduce weight.
Some people are looking at the exciting possibilities still left to be explored. A possible outcome may be radically new engine types in the near future.