1: make cars that take a lot less fuel.
They do. Unfortunately people want to buy the gas guzzlers. Personally, while I can understand getting an SUV if you live in a rural area, the people who buy them to drive around Manhattan are morons.
2: invest in public transport to reduce the number of cars on the road.
Once more, investment in public transportation depends in part on people deciding to use it rather than driving. Its impossible to fund expansions of subway systems if the trains are going to be half empty.
Actually most of the models that get better fuel mileage built in the US are ear maked for foreign markets. GM makes a few 40+ mpg cars that are only sold overseas. One of the issues are they don't have all the enviromental add-ons for the states or he safty features, this makes the cars lighter are more efficent, and not saliable here.
Public transportation sounds great but only if the city is designed for it does it work. Most east coast cities are tall and not spread out. The new cities are based on the car and and designed low and wide. This means thta the ppoulation base is spread out, which makles it harder to make profit. With little to no profit involved in the western cities public transportation can actually cost more than using a car. Now a few cities are starting to build upwards instead out outward and are redesigning themselves to work better with public transportation Long Beach CA being one of them. The problem is it will take them years to achieve a small increase and decades until the work will pay off. Being one of the major ports in the pacific will help keep the investors there were this can be done, not all cities are capable of this. I live in CA about 12 miles from downtown Santa Ana 15-25 minute drive to and from work. To use public transportation I would have to use 6 different buses and walk about 4 miles, also I would have to leave and get home allot later. I would have to leave my house at 4 am to make it to work and be back about 8 pm because of the schedules to catch the bueses. I can use the trainstation and get the time down but the train ticket is 4 times as much at which point it is cheaper to drive. The bus fares and the cost of driving are close the bus works out slightly less but the time lost is not worth it.
I have lived in New York were the Public transportation works, and have used it when travelling on the east coast. Everyone talks about using it but unless you live on the east coast or in an area designed for it, you will find it not worth it.
You want to make a difference look up the city planners and in the next election vote for the right ones and leaders that are capable of doing that. Who you vote in at the local level are more inportant than who the President is!