Picture of horizon on Mars, as seen by Spirit Rover, showing the litle speck that is Earth.

For a person who is 6 feet tall on Earth, the horizon appears to be 3 miles away.   That is without any obstructions in the view.  A person who walks at a fairly normal rate can cover those 3 miles in under an hour.

A Lexus can cover those 3 miles in under 3 minutes.

So would you say that "green transportation" is on the horizon?

I'd have to pick another term to describe how close we are to green-ness. Not on the horizon, that's for sure.  How about looking forward to it?  Hoping it happens because it has to happen?

None of the entries that have won the Lexus challenge questions so far have solved the problem of covering that distance between where we are today - almost totally dependent on fossil fuel - and where this challenge question wants us to go - in anything like the time it would take even a snail or slug to move 3 miles.

In some far distant future, probably after I have left this planet,  green transportation will be the norm and that excites me.  I wrote about it at some length for the last Lexus challenge question.  It's not a simple thing to get there.  I intend to choose a hybrid car for my next vehicle, or have my Toyota retrofitted to LPG or LNG.  That's my own personal decision to help the planet reach a goal of green transportation.

Choose your time frame or choose your planet. On Earth, the era of green transportation is not on the horizon. On Mars, the horizon appears closer, under 2 miles.  But every moving thing (that we know about) on Mars is an example of green transportation. As in the Spirit and Opportunity Rovers, which both use 100% solar power to navigate the rocks, sand and ice of Mars.  That horizon has been reached.  On Mars.  

Photograph courtesy of NASA/JPL/Cornell/Texas A&M Mars Rover program,  and my solar SUV, Spirit.