Hi
There is a Canadian company called Hymotion which claims to have built a plug in for Hybrid cars. (
http://www.hymotion.com/). I find the website of the company very confusing.
They claim that the product is still not available directly to consumers and they are in testing mode with the government and regulators.
They claim that it will work with all the Toyota hybrid vehicles. However, they are state as part of their FAQs that the Toyota warranty will be voided if you install their equipment, which is no good.