There have been a lot more ecological things happening in the last 30-40 years. One textile mill locally cleaned up its dye operations about 30 years ago, but recently moved overseas. Alabama power built several new natrual gas powered plants and converted some coal plants to natural gas, thereby greatly reducing air polution, especially around the Birmingham area. Cars are much cleaner today with catylitic converters and using lead free and less gas than older cars and trucks. Diesel is much cleaner and doesn't produce as much smoke.
There is a big problem. Most liberals want us to go with electric cars. There are several problems with electrics; range, charging time, strain on the power grid to charge a lot of cars, and cost. The technology isn't there yet.
Another problem. Most oil is supplied by only a handful of companies, thus a cartel. They do not want to put natural gas at their stations. Natural gas can match gasoline in speed, but not quite in range, but can be refueled in about 15 minutes with a compressor station, which is required at a gasoline station to compress the street gas to high pressure for vehicle use. The cost of a natural gas car or truck is the same as a gasoline one. The tanks are more expensive, but they do not have to have a catylitic convertor.
A slow conversion via about 15-20% new vehicles made to be diesel would switch over about 80-85% of vehicles to diesel over a 5 year period. Gasoline vehicles can still be made, but gradually phased out. This would cut about 30% of the imported oil. The higher mpg mandate of the feds will cut another 25%. This would basically cut the imports, thus keeping more of our money at home. Oil companies may not like it but they sell diesel anyways and would sell less overall fuel.
After this conversion, fleets, which account for about 25% of all American vehicle. If they have over 25 vehicles in a fleet it becomes cost effective to run compressed natural gas (cng). The fleet user can install a natural gas compressor and use natural gas in their vehicles. This could be government vehicles like postal trucks, city trucks and cars, county, and state, as well as fed vehicles. This would cut about 40% of the imports or about 20% of total oil use.
Plastics are a minor use of oil. Some plastics are made from coal, and some from natural gas. Most oil is used for fuel of some sorts.
Once vehicles are using diesel and natural gas, then maybe the price of hybrid equipment will come down. They can then be introduced into the mix to further cut oil use. Also, by that time synthetic oil can be made from coal and or algae at a competitive price.
FYI, we use about the same amount of gasoline today as we did in 1975. We had about 120 million vehicles then and 175 million now. So we are cutting use, it just takes time.