Where is the Environmentally Friendly Transportation

I remember as a kid (I was born in the 1960's) being told that one day soon gas and oil would run out. While many people lived in fear of this day, I was excited! I looked forward to the day when we would return to the horse and buggy. That day has still not arrived and cars are becoming slightly more efficient (although, as mentioned, still not as efficient as one would think). 

Well, time has passed and we are using cars (oil, and gas) more than ever. In fact, when I was young it was usually one car per family, now many families have two, or more, cars. It does not look like we will be going back to the horse and buggy anytime soon. 

Horses are very environmentally friendly (more so than cattle). They are a renewable resource. They need only grass (hay) and water. If worked hard some need oats or other grain too. While people often replace their car every 6 to 10 years, a well cared for horse can last much longer. Their waste is good for the soil. If you want to be blunt about it their remains can be used too, either as pet food, or to return to nature in a natural way to fertilize the soil.

On the other hand, horses were not always treated particularly well when they served exclusively as forms of transportation.  It was seeing cruelty to horses (and other humans) that inspired Anna Sewell to write her famous book "Black Beauty".  Even now improvements could be made to how carriage horses are treated when used to pull tourists around various cities.

What do you think, are horses the environmentally friendly transportation of the future?  Do you think there will be a time when we go back to the horse and buggy?