I have heard the debate for alternative fuel sources to environmentally power the motor car for about 35 years now and guess what? It's still no closer to where it was all that time ago.
Years ago we had LPG as a contender which in reality is not too bad as it is a very clean burning fuel....incidentally, the manufacturers and researchers are discussing the use of Range Extenders which could be powered by LPG...so full circle I think.
Full electromotive power....I think not, where's the electricity coming from. In the UK, not a chance! In the Nordic countries who are completely set up with producing electricity from Wind, Wave, Solar, etc....yes it can work.
Diesel....the manufacturers have now designed the new Euro 6 range of engines and exhaust after-treatment to become as eco-friendly as a petrol engine (almost) and this has cleaned the 'dirty diesels' act up for the remaining future of this power source.
Petrol, no problem....unless it's running badly or on open loop on start up but generally very efficient. Incidentally, the most efficient petrol engine is a race engine as it combusts to produce maximum power and extract full calorific content of the fuel leaving very little emissions.
Hybrid....now you're talking! probably the most efficient power source for a motor car. However, the manufacturers are now dropping their hybrid programme systematically to go to full plugin Electric Vehicles. Why???
Hydrogen...not while there are oil fields out there providing oil for refining and running power stations. Sad but true!
Attended a lecture by one of the Directors of BMW and he stated that their petrol and diesel engines would run into the next 10-12 years with no need to switch to EV. He also stated that autonomous cars will not ever likely be run in most countries unless there is a completely new build city to factor this in. Although they are producing full EV vehicles and supporting infrastructure for charging, it is still a problem with charge range, although this is also improving over time.
So, watch this space....meanwhile, I'll still enjoy both Petrol and Diesel until they take them from my cold dead hand