The fastest way to save money on gas is to combine three things: drive a little more smoothly, keep your tires properly inflated, and compare prices before you stop instead of filling up at the first station you see. None of these needs special equipment, and together they can noticeably lower what you spend each month. Here is how each one works, and how to make it a habit.

Start with how you drive

Your engine burns the most fuel when it is working hard, so the goal is to ask it to work hard as rarely as possible. A few habits make the biggest difference:

• Accelerate gently. Jumping off the line at a green light uses far more fuel than rolling up to speed. Think of an imaginary cup of coffee on the dashboard.
• Look ahead. If you can see a red light or slowing traffic a block away, lift off the gas early and coast instead of braking hard at the last second. Every time you brake hard, you throw away speed that fuel paid for.
• Use cruise control on open highway. It keeps your speed steady, which is easier on fuel than constantly speeding up and slowing down. Skip it on hilly roads, where it can over-accelerate on climbs.
• Mind your top speed. Wind resistance grows quickly the faster you go, so cruising a little slower on the highway is one of the easiest ways to use less fuel. It rarely adds more than a few minutes to a typical trip.
• Don't idle for long. If you will be stopped for more than a minute or so, such as waiting in a pickup line, it generally makes sense to turn the engine off (unless your car does this automatically).

Take weight and drag off your car

A car that carries less uses less. Clear out the trunk if it has turned into a storage unit, and take off roof racks and cargo boxes when you are not using them, because they add wind resistance even when empty. These changes are small one by one, but they cost nothing and add up over a year of driving.

Check your tire pressure monthly

Under-inflated tires have to work harder to roll, which means your engine does too. They also wear faster and can handle less predictably. The fix takes five minutes:

1. Find the recommended pressure on the sticker inside the driver's door jamb or in your owner's manual. Do not use the number printed on the tire sidewall, which is the maximum, not the target.
2. Check the pressure when the tires are cold, meaning the car has been parked for a few hours or driven only a short distance.
3. Add air until each tire matches the recommended number, and do not forget to check the spare if you have one.

Tires also lose pressure when the weather turns cold, so it is worth checking more often at the start of winter. Keeping up with routine maintenance, such as air filter changes and oil changes on schedule, helps your car run as efficiently as it was designed to.

Where and when to fill up

Gas prices are not the same everywhere, even within a single neighborhood. Stations compete on very local conditions, so two stations a few minutes apart can charge noticeably different amounts. A few practical rules of thumb:

• Don't wait until you are on empty. If the warning light is on and you are in an unfamiliar area, you will take whatever station you find, whatever the price. Topping up when you are at about a quarter tank gives you time to choose.
• Plan fill-ups along your normal route. The cheapest station is only a good deal if getting there does not cost more fuel than it saves.
• Notice the pattern in your own area. Prices often move up and down in cycles, and the pattern differs from city to city. Rather than trusting a rule you read online, look at the prices around you over a couple of weeks and see when they tend to dip.
• Look into fuel rewards. Many grocery stores, warehouse clubs and credit cards offer a discount per gallon. Make sure the saving is real and that you are not buying more groceries or paying more in fees to earn it.

Do the detour math before you drive across town

Chasing the lowest price can backfire. Here is a simple example. Say a station ten cents cheaper per gallon is on the other side of town, and you are filling a 12-gallon tank. You save about $1.20. If the extra round trip is 5 miles in a car that gets 25 miles per gallon, you burn around 0.2 gallons just getting there and back, which at typical prices costs roughly as much as your savings, plus your time. The lesson: a cheaper station is worth it when it is on your way, or when the price gap is large.

Compare prices nearby, not just the street sign

The sign you see from the road shows only one station. To know whether it is a good price, you need to see the others around it. That is where a price comparison tool helps. A free app like Find Cheap Gas lists nearby stations sorted cheapest first for the fuel type you pick, so you can see in a few seconds whether the station you are about to pull into is a bargain or a rip-off. You can use your current location or type a city, zip code or address, which is handy before a road trip.

Buy the right grade, not the fanciest one

Most cars run perfectly well on regular unleaded. Premium costs more per gallon, and it only helps if your engine is designed for it. Check your owner's manual or the label inside the fuel door. If it says premium is required, use it. If it says regular is fine, or premium is merely recommended, you are usually paying extra for no benefit. Diesel and E85 are separate fuels, so never put either in a car that is not designed for it.

Combine trips and skip unnecessary ones

An engine that is already warm uses fuel more efficiently than one starting cold, so a single longer outing generally beats several short ones. Group your errands into one loop, avoid rush-hour traffic when you can, and when a trip is short enough, consider walking or cycling. The cheapest gallon is the one you never burn.

A simple monthly routine

1. Check your tire pressure on the first weekend of each month.
2. Empty the trunk of anything you do not need.
3. Before each fill-up, compare nearby prices and choose a station on or near your usual route.
4. Buy the grade your owner's manual calls for, and no higher.
5. Drive smoothly and plan your trips.

Frequently asked questions

Does driving with the windows down or the AC on save gas?

It depends on speed. At low speeds, open windows cause little drag, while at highway speeds they increase it. Air conditioning also puts some load on the engine. The best approach is to use whichever keeps you comfortable at the least cost for your speed, and not to worry about it too much compared with the bigger habits above.

Is it worth waiting for the price to drop?

If you still have plenty in the tank, yes, a little patience can help. But do not let the tank run low just to chase a few cents. Checking nearby prices once you are at about a quarter tank is a good balance.

Do fuel additives improve mileage?

Most drivers do not need them. Regular maintenance and proper tire pressure are better places to start. If you are unsure, ask a trusted mechanic or check your owner's manual.

How much can I really save?

It varies with how much you drive, your car, and the prices where you live, so there is no honest single number. The more you drive, the more small habits are worth.