Increasing vehicle efficiency

A friend directed me to a Popular Science articles titled "The Race to 100 MPG"
http://www.popsci.com/popsci/automotivetech/e5690576b64fc010vgnvcm1000004eecbccdrcrd.html

I had some comments about the 3 advances mentioned.

• Cut weight and wind resistance: That is nice but there are some major problems with that. Cutting weight generally reduces the crash worthiness. I would hate to see that car hit even a mid-sized car at freeway speeds. I like efficiency but safety is more important. The size and shape of the car also reduce visibility of the driver which is also a safety concern. Finally I have a family of 4 with 1 more on the way so I could never dream of using that kind of car for anything but a commuter vehicle. I just don't think reducing weight and wind resistence will help much given the needs of car owners.
• Hydraulic drive system: I think this is excellent. One of the great things about it is that it could be fit into current car designs without major changes which should make adoption much easier. I like it that it is a component change so the engine could be made more efficient independantly which would make integration by the manufacturer easier. This sounds like something that could be in many new cars in just a few years.
• Jet Engine: First, this just sounds neat. Wouldn't you love to see your neighbor's face when they ask you what kind of engine your car has and you say "a jet engine!"? It would also be neat if it gives are car a "jet engine" sound (but much more quiet). Once again this appears to be an independant upgrade so that would really help.

As a developer I am a strong proponent of iterative development (many small changes instead of a few huge changes) and I think iterative effiency improvements will provide the fastest adoption also. I also like the electric motor and battery system from Tesla Motors.

I can't wait to see these things developed and make it into mass production!