A greasecar doesn't run on grease but a combination of diesel fuel and vegetable oil. You can convert pretty much any diesel to run vegetable oil.
An ecobeater is a car that isn't popular, pretty or even clean but gets you from point a to point b using the least fuel as possible.
The Volkswagen Golf is an adorable little German car that has roots going all the way back to the Volkswagen Rabbit. In the United States, the first and current versions of the golf were called Rabbits.