.
Since Christmas 2009, the fuel has become less of a problem. You still share the fuel between however many vehicles you own, but

click to enlarge
now it is possible to get extra fuel in ways that don’t involve paying real money for Farm Cash. Some of the presents you could get gifted contained fuel tanks. After Christmas, mystery eggs occasionally had fuel tanks inside. And, most usefully, you had the option to give a gift of 1/5 of a fuel tank to a neighbor- and they could gift you. At one point I had 43 fuel tanks. It was a nice secure feeling.
However, if you empty a fuel tank completely, it does disappear. If there is a little left in it, it will be the tank that refills for free. As long as you and your neighbors can send each other 1/5 tanks, you can keep a single tank going for a long time. Leave your gift refills in your gift box until your fuel indicator is almost empty. Then use a 1/5 tank. If you need to keep using your vehicles, keep adding a partial refill until you finish, so your total fuel tanks don’t go down. While you are waiting for the seeds to be ready to harvest, your fuel tank has a chance to refill for free, and you still have a lot of extra tanks left. If you feel like you are getting low, remember every time you level up or get a ribbon, you can publish the information with a personal message. Let your neighbors know you’d appreciate gifts of fuel.
* Note 2/4/2010 * 1/5 fuel tanks are not currently on the gift list. There is a good chance they will be back, and in the meantime, you may get fuel in a mystery box gift or in a special mystery egg. To maximize your chances for this, give gifts and help your neighbors, so they will so the same for you.
* Note 2/9/2010 * 1/5 fuel tanks are back - at least until Valentine's Day. If you send someone a Valentine, you can select the gift with a reward you want. One of the reward's is a 1/5 tank refill. You can send up to 10 Valentines a day. Send them until the 14th! With this action by Zygna, it looks like 1/5 fuel tanks may continue to be gifts or rewards intermittently throughout the year, for holidays. Keep an eye out for the chance to get fuel tanks, or get gifted them.
We will try to keep this article updated about the availability of extra fuel as we find out. If you know of a offering of fuel by Zygna which we haven't listed in this article yet, write a comment, and we'll put it in the article with a thank you.