From now on, every time your parents fill up at a petrol pump, they'll be putting fuel made from PLANTS into the car!
Under new rules, all petrol and diesel must contain a tiny bit of biofuel, which is made from crops like corn and wheat.
The Government wants us to use more of them to cut pollution levels.
But some scientists and eco-groups say biofuels could do more harm to the environment than good.
Campaigners protested outside Parliament on Monday, to try and stop the rules being brought into force.
They say in other countries, people have been forced from their land and rainforests have been destroyed, to make space for the crops to grow.
Biofuels are made from crops like corn
They also say it takes a lot of energy to make the crops into fuel, and warn using more biofuels will lead to a rise in food prices.
Mark Avery, from the RSPB, a charity which tries to protect birds and wildlife, said: "When you go and fill up your car, there may be palm oil going into your petrol tank that was grown somewhere that was a tropical rainforest two years ago."
But the Minister for Transport, Jim Fitzpatrick, said using more biofuels would help cut the amount of carbon dioxide being released into the atmosphere.
Carbon dioxide is one of the so-called greenhouse gases, which are thought to be warming up our planet.