Like HowStuffWorks on Facebook!

What can you do to your car to save fuel?

Go Veggie

If you're driving a diesel car, you have a couple options to save on fuel: filling up with biodiesel or doing a veggie oil conversion.

Biodiesel is an alternative diesel fuel made from processed vegetable oils. While it's possible to run a car on 100 percent biodiesel, it's more typical to find blends, or a mix of biodiesel and conventional diesel fuel. The naming convention for biodiesel blends tells you what percentage is biodiesel. For example, B20 is 20 percent biodiesel and 80 percent diesel. B50 would be 50 percent biodiesel. B100 is pure biodiesel with no diesel fuel added.

The upside to biodiesel is that you don't have to make any changes to your engine to use it, but it can be hard to find filling stations that offer it. In colder climates, be careful about filling up with pure biodiesel, since anything above B20 can gel in colder temperatures, which is bad for your engine. Stick to B20 or less in the winter months to protect your engine.

Running a car on biodiesel isn't the same as running it on waste vegetable oil, but it's possible to convert a diesel engine to run on plain old veggie oil.

Veggie oil conversion kits range in price from $300 to around $800, not including the cost to install. Since most vehicles can't run on 100 percent veggie oil, you'll essentially end up with two gas tanks: one for diesel and one for vegetable oil. Once your kit is installed, your car will start up using regular diesel; then you can switch to veggie oil once the car is warmed up. Before shutting off a veggie oil engine, you have to purge the oil from your fuel lines by switching back to diesel at the end of your trip, unless your conversion kit includes a pump that automatically cleans the fuel lines for you.

The best thing that you can do to your car to save fuel is avoid starting the car in the first place. Instead of hopping in the car, you can bike, walk or take public transit, and leave that gas guzzler at home. If your trip is too far to walk or bike the whole way, you can drive part of the way to your destination and then bike or walk the rest of the way. Even shaving a couple of miles off of your daily driving routine can add up to big savings at the pump over time.

For more great information, check out the links on the next page.