Originally Posted by Pharmacist

actually climate change and global warming has already been documented as true, and you should care because it will have lots of negative consequences to the planet and people. and keep in mind that internal comubstion engines are an old and outdated design from the middle of last century. it's also extremel inefficient, usually converting only 10-20% of fuel to kinetic energy. on the other hand, most "green" technologies in cars nowadays aren't really all that better than internal combustion engines. like others said, those battery packs are very highly toxic and loaded with extremely poisonous heavy metals. manufacturing and disposing of them are both dangerous to the environment too. also the electricity had to come from somewhere, usually by burning fossil fuels in power generation plants. gas-electric hybrids are a bit better than normal cars for the environment, but their fuel savings is not much and they tend to be underpowered and costly.

i believe the best way to protect the environment would be stop focusing on the engine and fix the rest of the car. Put cars on a diet by using lightweight composite materias for the body, remove excess and unnecessary features that an owner won't use, trim the interior, and use lightweight materials for suspension, wheels and chassis components, glass windows, body panels, etc.... Shaving off weight would help a lot with fuel mileage. if the average weight of vehicles on the street goes down from say 4000 to 3000 pounds, fuel consumption would automatically go down by 25%. also more effort should be put into harnessing braking energy. most kinetic energy in a car goes to heat the brakes and then goes into the air during braking. the car will have to burn more fuel to get back to speed. if there was a system that harnesses and stores the kinetic energy of a car slowing down, then this energy can be reused to accelerate the car up to speed again in lieu of having to burn more fuel. It would be something like the KERS system F1 experimented with last year. since the bulk of fuel consumption is used for accelerating a slow car, a kers system or equivalent if made efficient can lead to huge savings in gas mileage.