Is premium gas worth the premium price?

These days, many people at the pump are passing on premium gas. The reason is obvious: Any kind of gas costs a premium these days. So if you don't need premium, why use it?

While car lovers can debate the merits of using premium, one thing's for sure: Cars that are designed for regular fuel get no benefit from using premium. Using it may not hurt anything -- other than your wallet -- but only specially designed engines can take advantage of premium fuel.

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In the following video, I'll drive the point home. Check it out, then meet me on the other side for more.

Despite what you just saw in that video -- that the word "premium" is nothing more than a marketing term -- many people still buy into common myths, like "Premium gives me more miles per gallon" or "Premium fuel will make my car run better." While every company uses a different mixture of fuel additives, and some can give fractional benefits, you won't notice the difference. (For real ways to improve your mileage, take a look at Fueleconomy.gov.)

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Another common myth is: "I need premium because it cleans my engine." All fuels have detergents that clean your engine, some better than others. While premium does have more detergent, most fuels will get the job done. NPR's "Car Talk" says it's even OK to use gas from those "el cheapo" stations, as long as you alternate with gas from bigger brands.

There is one "myth" we're reluctant to classify as such, because nobody seems to know for sure. Some people say that using fuel with the wrong octane rating will void a warranty. Both "Car Talk" and Cars.com say it's not likely but not impossible. This CNN article says Smart USA, at least, will void warranties for regular use of the wrong fuel.

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The best bet is to check your driver's manual to see if it says "required" or "recommended." If it's the former, you should probably listen, but if it's the latter, ask a trusted mechanic or consult the manufacturer.

While using premium fuel in a car that's not designed for it is a waste of money, let's talk about doing the opposite, which can save you money -- but also offers a few potential problems.

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Using regular-grade fuel in a vehicle designed for premium

Can you do it? Absolutely. Most people should, but there are some exceptions, some precautions you should take, and some minor differences to be aware of.

Using lower-octane fuel with an engine designed for high octane can result in some performance reductions that vary between models, but most people aren't going to notice. We're talking half-second differences in accelerating from zero to 60 miles per hour, and losing some horsepower at racetrack speeds. If those kinds of differences matter to you -- or if you want to learn the tech and science behind your car's fuel -- check out this article from Car & Driver.

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There's also a small risk of wearing your engine out faster, a risk that's higher if you're driving a car that's more than 15 years old. Fortunately, you can gauge this risk pretty easily: If it's a problem, your car will start making a sound called "knock," which sounds like it reads. That's a sign that your car isn't handling the fuel well. If you hear it once or twice, you're OK. If it becomes a regular occurrence, you should switch back to premium. Ignoring the problem can cause permanent engine damage.

Most modern cars won't run into this issue, because they have sensors that check how well the fuel is working with your engine and make adjustments automatically.

You're also more likely to face "knock" if your car is under extreme conditions and needs the extra performance -- in higher temperatures with low humidity (the desert), when hauling heavy loads (moving day), going up steep inclines (mountain country) and driving at super speeds (Indy 500). So if you live in an area with these conditions or haul heavy loads for a living, premium might be more important.

But for most of us, "premium" refers to the price, rather than the quality, of gas at the pump. See the links below for more ways to save on gas.

More from Money Talks News and MSN Money:

• 28 ways to save on gas
• Gas-saving devices a scam?
• Motorists' dream: Gas at 6 cents per gallon
• GM accelerates Volt rollout
• Why $4 gas will cause less pain this time 
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