Looks like the leaked FarmVille Fuel for Coins image was legit, and the limited time promotion has already appeared in the game. Here's how it works: If you're above level 20 and earn a new Co-Op farming medal, you will be able to purchase fuel using coins, once a day. There are two fuel for coins options -- buy one fuel refill for 10K coins and five fuel refills for 50K coins.
To purchase the fuel, head to the FarmVille Market, click on the Vehicles tab and then start buying. Since this offer will only be around for a limited time, we suggest putting the pedal to the medal to collect as much fuel as possible -- those gas-guzzling tractors aren't going to refill themselves.
How much fuel do you have stockpiled in FarmVille?