Chevy Cruze Fuel Economy

How to Get Better Fuel Economy

My Chevrolet Cruze is rated for 28MPG city and 42MPG highway, yet I average 39.5MPG with 73% city driving and get over 50-55mpg fuel economy on the highway. I’ve made no significant modifications to my vehicle, and my car is not a hybrid! Let’s talk about how to get better fuel economy. This article will share my tips, techniques, and tricks for improving fuel economy that anyone can use. These are all practical and simple techniques that don’t require any significant mechanical modification or extra expense on your part.

Mechanical Checks for Improving Fuel Economy

Lets start with the simple stuff; mechanical. The behavioral techniques I’ll mention later will be useless if your car has mechanical issues. The first key to achieving great fuel economy is making sure that your car is running in optimal mechanical condition.

Tire pressure/Tires

This should be obvious, but some people are too lazy or they just forget. I’m guilty of this. On my last car, I spent 3 months chasing down a condition in which my car pulled ever so slightly to the right and I was averaging 20mpg city/highway when I should have been averaging 24-26MPG. I only realized when I put snow tires on that one of the tires was low. That extra rolling resistance from under-inflated tires was killing my gas mileage! If you’re buying new tires, narrower tires are better than wider tires for fuel economy. Lower rolling resistance, less air drag.

Tire’s should be inflated according to the manufacturer suggestion. I say suggestion because its just that; a suggestion. This is a number that is provided for a “best compromise” situation. A lower tire pressure will soften the ride and provide better dry traction, but will cause more heat due to rolling resistance and reduce fuel economy. Too low of a tire pressure can result in catastrophic failure. A higher tire pressure will stiffen the ride, but will improve fuel economy as much as 3-4mpg.Tires can be safely inflated to their maximum sidewall pressure without any danger of catastrophic failure, as this is set by the manufacturer of the tire. Reports on cleanmpg.com forums indicate that tire life is also greatly extended when tires are inflated beyond the car manufacturer’s suggested pressure. Most people who inflate to the sidewall recommended pressure end up replacing their tires due to dry rot well past the tire’s warranty mileage, not due to balding, loss of tread depth, or uneven tire wear. It is up to you to determine what the best pressure is for your tires based on the information provided in this section.

At the time of writing, I’ve logged 14,000 miles on my Chevy Cruze Eco’s tires at 50PSI (maximum sidewall pressure being 51psi), measuring tread depth across the tire with a digital tread depth gauge accurate to 1/64″ increments. At this time, my tires are wearing 100% flat without any abnormalities.

Mechanical maintenance

This isn’t so obvious, but it should be considered. If you drive an older car and your fuel economy is severely below that of its EPA fuel economy rating, something is wrong. Spark plugs/wires and O2 sensors do go bad after a while and need to be replaced. MAF sensors need to be cleaned (CAREFULLY or with a MAF cleaner aerosol can), and a good seafoam wouldn’t hurt either. Air and fuel filters are a given. 180 degree thermostats might be nice for performance, but 195 and 215 degree thermostats will get you better fuel economy. If you have a bad wheel bearing or a dragging brake caliper, get it fixed because it will end up costing you more as a result of poor fuel economy and uneven tire wear than it will cost you to get it fixed.

Fuel/Engine Maintenance

Do not waste your money on mid grade or premium fuel when your car is designed for regular fuel unless you know for a fact it has a lower ethanol content. Higher octane fuel in a naturally aspirated, low compression motor is a complete waste of money. The opposite is true if you have a boosted or forced induction motor that is equipped with a turbocharger or supercharger. In those instances, lower onctane fuel can not only damage your engine, but will retard spark timing and consequently reduce efficiency.

I personally recommend using top tier fuel. If you use top tier fuel, it will contain detergent additives that claim to allow your fuel to burn cleaner and leave fewer carbon deposits. This is more of a long-term fuel economy technique, as carbon build up will reduce the efficiency of your motor. It is highly recommended that you keep your fuel and intake system maintained with fuel system cleaners and intake cleaners such as seafoam that help clean the engine from carbon deposits.

Weight

Chances are, you don’t need all that junk in your trunk. Less weight means you use less energy to get moving. Your car is not your closet, so if you don’t need to be carrying a bunch of weight around, store it somewhere until you need it. While a small reduction in weight will not make a huge difference on its own, it will add up over time and will combine with other fuel-saving measures you may take to give you a significant boost overall.

 

Behavioral Techniques for Improving Fuel Economy

Once your car is running in its optimal conditions and you’re getting “decent” fuel economy (compared to your car’s EPA fuel economy rating), we can move on to some behavioral techniques.

Turn off your heater.

In the winter, if its not unbearably cold, suck it up and leave the heater off until the car warms up. The reason for this is that most cars will run in open loop mode until it reaches ~160 degrees F. During this time, the engine’s PCM (computer) will ignore some of its sensors (including the MAF) and run rich until it has warmed up enough for the sensors to all be functioning correctly. If you run the heater while the car is dumping fuel to try to warm up, you’re just prolonging the time during which it stays in open loop mode and wasting additional fuel. This is because the heater core essentially acts like a radiator through which you’re forcing cold air. It may not sound like it, but it does make a significant difference. You can turn the heater back on once you’ve reached ~180 degrees F.

Watch your RPMs.

You’ll burn more fuel if you accelerate more “spiritedly.” Your shift points in an automatic transmission will naturally be quite limited, but your throttle won’t be. For manual transmissions, try to get into your highest gears as soon as possible. To use my Cruze as an example, I shift into 2nd gear as soon as possible, hit 2000RPM in 2nd, then keep RPMs below 1500 from 3rd through 6th gear. I’m in 5th gear at 35mph and 6th gear at 40mph, cruising at 1100RPM, quite literally sipping on fuel. Since I know this is easier said than done, here’s a method you can use. Pretend there’s slushy snow on the ground and accelerate accordingly. If a few people pass you, no big deal. The difference in a few car lengths will be mere seconds added to reaching your destination. While you may feel like you’re going slower, in the end, you will probably reach your destination at the same time, give or take a few seconds.

Watch your speed.

Driving on the highway at 70mph might get you there 1-2 minutes faster, but you’ll burn a lot more fuel. The ideal speed for fuel economy for most cars seems to be 55-65MPH. It takes exponentially more fuel to cruise for each incremental increase in speed. As a very rough example, let’s assume that your vehicle can get 40MPG at 55MPH. Say you increase your speed by 10MPH to 65MPH, and your fuel economy drops by 5MPG to 35MPG. If you increase your speed another 10MPH to 75MPH, your fuel economy will likely drop by 8MPG to 27MPG. While the exact increase in fuel consumption will be dependent on each specific car, the principles of aerodynamic drag will not change. Stay in the right lane (or 2nd to the right lane in the case of wide highways) lane and keep up with the speed of traffic.

Turn cruise control off in town.

That is, unless the road is completely flat. This applies mostly to in-town and back-road driving, as interstate highways/freeways will be limited to smaller and longer grades/inclines during which cruise control is fine to use. In city driving, your car will automatically adjust throttle to keep the car going about the same speed when it reaches a hill, which isn’t ideal for fuel economy. In an automatic transmission, your car will probably downshift in order to have enough power to make it over that hill at a consistent speed. Accelerate lightly before approaching a hill, allow the car to decelerate while climbing the hill, and accelerate lightly as you’re going down the hill to get back up to speed. Of course, this only applies to smaller hills, but that’s the general concept.

Conserve Energy.

This one is a complete change in the way some of you drive in-town and is arguably the biggest factor that will affect your fuel economy. Some of you will follow the car in front of you blindly or drive the same speed and slam on the brakes when the light had been red for a while. Every time you accelerate, you use fuel, which turns into energy. As your car is moving, it is carrying energy. That moving energy is lost (wasted) whenever you step on the brakes. So, how does one drive to keep from wasting energy? Let me give you an example. I used google maps for this to try to create a visual for the scenario I’m about to describe.

Fuel Economy

Above is one of the routes I take to get home every day. In the above picture, you may be able to see a left turn lane as well as a main lane, with peoples’ brakes on, as the light ahead is red. Imagine your speed is 45mph as this is a 45mph zone. What most people will do is follow the car in front of them regardless of what the traffic light is. What I do is let off the gas the moment I see a red light at that kind of distance. If the light stays red, I’ll have coasted to 25-30mph before I have to hit the brakes. This increases the life of my brake pads and I’ll be in the same position as if I had followed closely and hit the brakes as hard as the person in front of me.

However, what happens 50% of the time is different. Usually, I’ll see a red light at this distance, release the throttle, and coast at a lower speed as I approach the intersection and the cars lined up at the red light. By the time I get closer to the intersection, the light will have turned green and the cars will have started moving. Here’s the critical moment. By the time I reach the car directly in front of me, it will have accelerated to 15, maybe 20mph, and I will be able to continue moving at that speed instead of coming to a complete stop. That’s 20mph of moving energy I did not lose by watching what was happening in front of me and driving accordingly.

If I had followed the car in front of me more closely, I will have come to a complete stop and immediately have to accelerate again from a complete stop. This driving style requires you to fully understand that in 60 seconds, you will be in the exact same position whether you keep a constant speed until you have to brake and come to a complete stop, or cruise without using fuel and reach the intersection at a later time. The fact that it takes you longer to reach the intersection means that the cars are likely to have started moving by then, and you will have lost less moving energy in the process, and used less fuel. You will feel like you’re moving slower, but you will notice that you will always be near the cars around you and thus will have lost no time at all.

To fully understand this concept, you have to look at your fuel economy as energy. When your fuel is used to propel your car, the energy from the fuel is converted into inertia. Rolling reisstance and aerodynamic drag aside, the only way your car will stop is to waste energy – by braking. When you apply the brakes, that energy is wasted as heat, so your mission is to try not to waste that moving energy through heat in your brakes.

Here are some questions you can ask yourself.

  1. Could I have avoided coming to a complete stop?
  2. Could I have predicted what would happen in front of me?
  3. Was it necessary for me to keep a constant speed?

Do you have a manual transmission?

If you’re driving a newer car with a manual transmission, keep the transmission in gear while coasting to a stop if you know you will have to stop. So long as you’re above idle, the engine will actually shut off the fuel injectors and allow the transmission to turn the motor over, using zero fuel. While automatics will also do this, you have greater control with the manual. Don’t put it in neutral when coming to a stop, leave it in gear until your RPM drops low enough to need to shift out of a gear. This concept is called DFCO (deceleration fuel cut-off). It is a feature in car computers that has been around for the last 15 years. Take advantage of it.

Choose your route wisely.

If you have several stops to make during a single drive and are not limited on time with regard to when you get there, drive to the farthest destination first, then work your way back. Doing this allows you to make your initial driving session longer, thus allowing the vehicle to reach full operating temperature. If you make many short trips, your car may never reach full operating temperature, and you will be wasting fuel in open loop mode. In addition, if your car is equipped with an oil life monitor, your car will reduce your oil life as a result of your low-temperature driving.

Don’t idle.

Your car doesn’t actually need to warm up for minutes when you first start it up before you leave. This only applied to older vehicles that needed a substantial amount of time to allow oil to circulate and to fill the hydraulic lifters and is not an issue with newer cars. Get on the road 15 seconds after you start your car. If you’re waiting on a passenger, turn your car off until they get there. Basically, unless you’re moving or know you will be moving soon, turn the car off. To take this one step further, take the extra effort to go into a fast food place instead of going through the drive-through, as the drive-through will keep your car idling and wasting fuel for no good reason.

 

Things you should NOT do to improve fuel economy

You may read of some methods that I may not have mentioned. I’d like to warn you that some of these are bad ways to improve fuel economy and can even land you with a hefty fine.

Drafting (closely following) a truck.

People love doing it, but its not only unsafe; it’s illegal. You’re a pain in the you-know-what of truck driver because they can’t see you. Furthermore, you have zero time to react to debris that gets shot in your direction out from under truck tires. Trucks will kick up rocks and shoot them into your front fascia and windshield. Not only does it ruin your paint, but it can also crack your windshield. I’ve seen a truck kick up a broken hammer head that someone lost on the side of the road. Take a guess as to what happens if that comes flying toward your windshield at 70mph. I’ll give you a hint; it doens’t bounce off like a pebble. It could result in your death. If you wish to take advantage of the draft another vehicle creates, follow at a safe distance that allows the vehicle in front of you to see you and allows you to react to a situation that you may not otherwise be able to see.

Using higher octane fuel

Its useless and will not improve your fuel economy unless you’re boosted (supercharged/turbocharged) or your car has a higher static compression from the factory, such as the Northstar V8. Unless your manufacturer specifically recommends the use of higher octane fuel, do not use higher octane fuel, as it will not provide any power or fuel economy gains. There are a few exceptions to this, such as the 1.4L Turbo engine in the Chevy Cruze, which will run on 87 octane, but will run better on 89 or 93 octane. However, these are exceptions, not the norm.

Driving significantly under the speed limit or accelerating like you were down a few cylinders.

This makes you a road hazard. Drive the speed limit or keep up with traffic, unless you expect to come to a complete stop or are approaching a small hill. Driving significantly slower than the speed of traffic forces other cars to perform additional maneuvers to get around you.

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