Side-cars are still not so popular in the bigger bikes in my country, but about 2 weeks ago I spotted this Harley-Davidson Sportster 1200 with one.
Well, it may not be deemed so "eco-conscious", but considering all the energy-expense and resources consumption involved in its manufacturing process and later for the replacement parts let's say it at least fares decently compared to some random convertible car even if the fuel consumption would get the same average...