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Are there any free / very cheap mods for improved MPG?

30K views 64 replies 27 participants last post by  NickD 
#1 ·
I searched through different threads but can't find anyone that has free or very cheap mods that increase gas mileage. I don't care about performance, just looking for improved gas mileage on an automatic LTZ. I would LOVE to increase my 34mpg up closer to 40mpg. This may be a tough thing to accomplish.
Any thoughts or links for this newbie??
 
#2 ·
40mpg is probably not going to happen unless you drive 45-60mph and drive only highway. Most cruze Autos don't hit those numbers.

You can however bypass the air intake resonator and its accompanied plumbing.

Remove the airbox and you'll see a tube that runs down into the fenderwell with two plastic fasteners. Remove the fastener caps, then the fastener anchors, and pull up firmly on the tube and it will come out. There should be a gasket at the bottom of it. If not, its probably still on the resonator. Stick your hand down there and grab that as well and keep it with the tube you just removed. Put the intake back together and enjoy some free extra power and a slight fuel economy increase. Oh, and you'll be able to hear the turbo now too.

I would also run at least midgrade fuel (89 octane). It has been tested and proven that these cars produce knock with 87 octane, and although the car will run just fine with it, it will run better and get better fuel economy with 89 octane. The improvement outweighs the extra cost of the higher octane fuel. I can't say I've noticed a difference going from 89 to 93 octane though.
 
#7 ·
You can however bypass the air intake resonator and its accompanied plumbing.

Remove the airbox and you'll see a tube that runs down into the fenderwell with two plastic fasteners. Remove the fastener caps, then the fastener anchors, and pull up firmly on the tube and it will come out. There should be a gasket at the bottom of it. If not, its probably still on the resonator. Stick your hand down there and grab that as well and keep it with the tube you just removed. Put the intake back together and enjoy some free extra power and a slight fuel economy increase. Oh, and you'll be able to hear the turbo now too.
I have been looking for a "how to" for this that also shows pictures. Does that exist anywhere here on the site? I like looking at the pictures before I jump in so that I can ask any obvious questions.
Is this basically removing the air inlet tub from the bottom of the air box? If so, is the air the engine would be sucking in just going to be engine compartment air?
 
#9 · (Edited)
#5 ·
We skipped a $10,000 rebate on a Silverado and a $7,000.00 rebate on an Impala for these reasons. But kind of took a raincheck on the Volt, would never get our extra $26,000.00 back and maybe a bit of headache with maintenance cost afterwards.

We don't necessarily believe in rumors, but when they talk about 6-7 bucks a gallon for gas, tend to believe rumors like that. Suppose to have a known supply of natural gas for the next four thousand years, and add another 8,000 years of methane to that, depending on your source for this kind of information. Much cleaner burning fuels, but still stuck with an oil controlled congress. That is the major problem. Nothing is being done about nuclear fusion either. Enough deuterium in one gallon of seawater to power your vehicle for years.

Instead we are going backwards by using corn and exporting our technology to China alone with our jobs.

Yes, tire pressure plays a role, always has, always checking my tires, but don't have to do that anymore, OnStar is as pressure monitoring systems are now mandatory on all vehicles. And that will only cost me a couple of hundred bucks extra per year. Will no longer pay four bucks for four brand new valve stems, if they leak or the battery goes bad, will cost more like a 160 bucks. But this is the governments way of making sure you keep your tires filled. The EPA with over 155 different blends of fuel doesn't help either.
 
#13 ·
Amen to the taking a raincheck on the Volt $42000 with one option(the car) it is new technology and great if you don't have to go farther than 100 miles or get stuck in traffic which turns out to be downfall of the hybrid. Honestly, how long will the battery last and how much to replace.

Checking the air pressure does not require On star. They will send you a note but just check it on you DIC. That will tell you the tire pressure. And if you look on your driver door jam it will tell you the recommended tire pressure is 35 PSI on all 4 tires and 60 on your spare. Sorry, I am one of the few that have one of those and used it already! LOL
 
#12 ·
So why does a carburetor engine require a choke or a fuel injector engine require enrichment to start a cold vehicle. Its because a cold engine does not evaporate the fuel and a lot more of fuel is required to initially start it. The colder the weather, the more enrichment or choking is required.

Why is the thermostat in the Cruze set at 225*F instead of the long time standard of 195*F? To increase the vaporization of the fuel to increase the efficiency. Removing that air intake is exactly backwards, not only in theory, but in practice. Its true that colder air is far more dense, but then you also have an O2 sensor to compensate for that. Nitro works great for getting a very dense air into the combustion chamber, but a lot of fuel has to be added to it for proper combustion. A power increase, but certainly not a fuel economy. A nitro equipped vehicle hitting 200 mph, can empty a 27 gallon fuel tank in under ten minutes.

If you want better fuel economy, just leave that air intake like it is, was done that way intentionally to get a few mpg more. Nothing gives worse fuel economy than short trips with a cold engine.

To help with fuel evaporative problems, EPA has mandated oxygenated gasoline to help reduce CO emissions, but works 180* out of phase with fuel economy. Worse yet, paying four bucks a gallon for oxygen and not getting the same heat value out of that fuel. So fuel economy is far worse during the winter months. Living in northern Wisconsin, we were the last to get that, but started that about 15 years ago. All of my vehicles are getting far worse fuel economy in the winter months with this winter gas. Like 20% poorer on some vehicles. And the price of gas this time of the year set a new record for high prices. But trying to learn how to enjoy being screwed.
 
#14 ·
The 1.4T is intercooled, which has far more effect on the air temperature than the outside air. I've seen 70*F engine air temperatures when the outside air has been well below freezing. The intercooler heat-soaked and heated up the air flowing across it. And, the OEM intake was designed with all its baffles/chambers to reduce noise and prevent little critters from nesting in the airbox, not get great MPG. Ridding the intake of those pre-airbox baffles leaves one with a freer flowing intake. Being a turbo engine, flow is a friend up to a point.
 
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#17 ·
Hypermiling.... free... and i'm learning... Gunna squeeze ever little oz of MPGs that I as a human can... :D
 
#19 ·
#22 ·
...the free'est & cheap'est FE mod is to simply "...lift your foot off the accelerator pedal...", ie: drive slightly slower, at 50-55 mph, instead of 60-65 mph.
 
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#23 ·
At the risk of sounding like a jerk, I'm dead serious when I say don't drive. Seriously.

Nothing will save more money. Carpool. Ride your bike to the plaza that is only a mile or 2 away. Combine your trips with the furthest destination first (more efficient this way). Also go to the do it yourself car wash instead of the automated drive through. Turn your car off whenever you can and get out of the car.

Since I started using these little simple tips.. like riding my bike to the other side of my 2 mile long campus, my MPG has shot up simply because the trips I'm taking are necessary instead of convenient. It helps alot.
 
#26 ·
I have to say something about tire pressures.

A couple of people are flatly stating that the pressure should be 35psi. My Cruze LT has 30psi on the door tag. So what I want to know is what the door tag says for other trim levels. And also what tire and wheel size is on the car. I know that a 17inch size is available in some cases, and there are also the LRR and 'standard' tires as well. So it very well could be that there are different pressures called for between them all.


It is important to follow Chevy's tire requirements. It has all been carefully thought out, engineered, and tested. Adding a significant amount of extra air to the tire can affect handling and shortening the life of the tire. You can be creating a safety hazard for yourself.
 
#28 ·
Respectfully, this is not true. It is not important to follow Chevy's tire requirements. Their requirements are an "optimal" pressure.

If you reduce pressure, you gain traction and ride comfort, but sacrifice fuel economy. You also compromise tire wear and have more of a possibility of a blowout. Contrary to what may make sense in your mind, tires blow out due to insufficient pressure, not too much pressure. I've never seen a tire blow out because it was given too much pressure; its always the other way around.

The only way you'd be creating a hazard is by reducing the traction ability of the car by increasing tire pressure. In fact, you gain tire life by increasing the pressure of the tires. You may be thinking of the pictures you've seen at your local tire store where the inner section of the tire is worn more than the outer section, and they use that as a recommendation to ensure that your tire pressure is accurate. This is not only false, but also misleading. So long as your tires are rotated at least every 10,000 miles, they will wear evenly regardless of tire pressure.

This was discussed endlessly on cleanmpg.com forums and the consensus was that increasing tire pressure to the maximum recommended on the sidewall will have the exact opposite with regard to tire wear as most people think. People who have used tire pressures above what the manufacturer recommends have gone 80-100k miles on tires rated for 40-50k. They end up having to replace them not due to wear, but dry rot.

Keep in mind that a tire with a higher pressure will have a lower rolling resistance. It will have less contact on the road per revolution, thus reducing its wear.

My eco states 35psi. It will depend on the wheel size and tire type, is my guess.
The truth is that tires will respond differently to different tire pressure. GM knows what they outfit from the factory, but they cannot make a valid recommendation for every tire you will install on the car after that. For example, 32/32 was the recommendation for the factory 215/65/15 tires on my 95 Regal when I bought it. I installed 235/60/15 tires shortly afterward and the front tires always looked flat. I needed to increase pressure on those to 44psi, the max on the sidewall, so that they would actually be reasonably inflated. I still got 45k miles out of them, which is exactly what they were rated for.
 
#32 ·
Twelve years ago, the DOT came into our city, did an evaluation, installed over 30 traffic lights, most with no right turn when red, dumped all the yield signs and replaced them with stop signs, and reduced practically all the speed limits. We have three major state highways running through town, rather than bypassing the city, tore down buildings and put major expressways down the middle. City hired a civil engineer to program all of the traffic lights, didn't know what he was doing, could spend ten minutes at a traffic light that was red to make a now forced left turn with not a soul in sight. Plus added hundreds of street lights, city is brighter at night than in the daytime. All at a time when energy costs are skyrocketing.

Year later, 9/11 came along, more than doubled the size of our police department with three new undercover cop cars. With nothing else to do except issued tickets. Got so bad, city had to elect a judge to hand the fines. Then came ethanol in gas. Takes an extra 15 minutes to cross town, engine spends more time idling than anything, solution, hybrid vehicles that really don't work in cold weather, and only work if you can coast a mile before stopping. Everyone is so impatient, can't do that.

Read they did the same thing in LA where they added 45 minutes to go anywhere. They also moved a historical train station that hasn't been used in over 44 years, is now a Japanese restaurant. The old Wisconsin Central RR was sold to the Canadians and instead of 20 freight cars, pulling trains 1.8 miles long. Nothing in town uses railways anymore, all 18 wheelers, did built a couple of overpasses on dead streets, main street in downtown is blocked for twenty minutes because the city imposed speed limits on these super long trains. Traffic blocks up for a mile.

Did build bike trails, they are nice, but don't go anywhere, but my dog and I like those, built a overpass over the new expressway and railroad track, think my dog and I are the only ones that use that, but when we cross over, have to do a U-turn because it doesn't go anywhere. Do have a major clinic and hospital in town where ten thousand people come in everyday, didn't do a thing with that, but built a school on one of the two lane access roads, loaded with cops, 10 mph speed zone, and kids constantly crossing during the rush hour.

Our county roads are the same, for every **** bar on these roads, not a soul in the daytime, cut the speed limit from 55 to 35 mph, not just for the bar, but 3/4 of a mile before and after. Yes you see cops hidden to enforce those speed limits.

So you want to save gas and get better fuel economy? Could try moving to a different country. USA is ran by idiots. Could try split fire spark plugs or hang a magnet on your fuel line. Or get a hybrid. Performance is also key, if you are trying to get on an expressway. With just about everyone, thousands of suburbs popped up jamming them with millions just going back and forth to return a DVD. Not good if you are traveling cross country. Sleeping during the day and driving at night does help a little, but not when driving through Chicago.
 
#61 ·
Couldn't agree with more Nick. Our stop signs make no sense where we live either and waste a ton of fuel. We now have left turn yellows. If you are at stop light and in the left turn lane you no longer get a green arrow but a yellow arrow. You now have to wait for the on coming traffic to go by before you turn. You NEVER get a green arrow. So if there is ton of traffic and you could never go you could be sitting at that light for two or three cycles. This is insane. Are we just changing things cause that department got a budget and needed to spend the money. Makes no sense.
 
#34 · (Edited)
...things that help you save gas, because they make you slow down?
 
#37 ·
....:th_salute: I salute you!
 
#40 ·
Its just that while sitting waiting for a red light to turn green, either your instantaneous or average mpg is showing ZERO! In SAE Engineering, talking about a system whereby when your Vss is outputting zero, will automatically turn your engine off, stepping on the gas will start it up again. Without too much discussion on thermal cycling that really wrecks an engine.

Talking about instead of directly driving the AC compressor to switch to a less efficient electrical one, so you don't bake while waiting for that light to change. Also dumping the starter and combining that with the alternator, but this isn't new, Kettering did that in the very first electrically started Cadillac in 1912.

So asking about modifications to save fuel? Is is already being discussed and even done already in some European vehicles, but without the electric AC, claim Europeans are tougher than Americans. Really don't think is is a DIY project, but can switch off your ignition while parked at a light. But will be paying a price with thermal cycling and starter wear.
 
#42 ·
I believe the fuel economy increase in your change between coasting and leaving the car in gear has more to do with external influences than with whether or not you're leaving it in gear.

I am curious to see what kind of fuel economy you pull after removing that intake duct.
 
#44 ·
I have not pulled the air intake duct just yet, but my driving habits have increased my overall mpg to 35.79mpg in this 2011 Cruze LTZ automatic. I have also tested the theory of letting the engine slow the car down versus shifting into neutral and coasting in. My test was conducted in the same location, same direction, same weather and the AVG MPG meter was re-set roughly 15 miles prior and had stabilized by the point of the test. This test was conducted on highway conditions. When letting off the gas and letting the engine slow the car down, my mpg went DOWN (per meter). However, when I shifted into neutral, the AVG MPG meter actually jumped up substantially over 4mpg. With this driving style, I am getting around 510 miles per tank of gas. This is EXACTLY why I bought the car and am very happy with it!
The only downfall that this car has is the cold shifting for the automatic... this is easily fixed by using manual mode, but still sucks to have to do that.
 
#43 ·
Will do, and thanks for all the tips and tricks. I have always used the 'throw it neutral' theory to squeak out the best mpg I could. I do not believe there were any other external influences that would have affected my testing. Weather was similar and there were no differences in traffic/lights/stops.
In my past, I have driven an AWD Chevy Trailblazer SS to a tad over 19 mpg and used this method of neutral as much as I could. Also, my Cadillac CTS-V is a 6spd manual, and that car runs 21-24mpg using the neutral method (not bad for 550 rwhp!!). I have tried many things on cars to get the best gas mileage I can and it is my opnion that throwing it in neutral to coast to a stop is the best for me. The only vehicle that I do not do that in is a Chevy 1500 4x4 with the 5.3L (cyl. shut off) and the best that truck can do is 17.2mpg.
 
#49 ·
There is something I'd like to add: on my previous vehicle, there was a manually actuated valve separating the heater core circuit from the rest of cooling system. I found this advantageous in winter, as, (when closed) the engine came up to temp in less time, as it had that much less coolant to warm up. Once nearing the thermostat set point, I'd open said valve, engine would cool somewhat from the inrush of colder fluid. But by that time, the system was already out of it's 'rich' zone. Also, keeping hot coolant from heater core in summer was an advantage in summer, for obvious reasons. (Said valve was cable actuated from the inside, and was part of the 'temp' lever on the cabin's ambient controls).
 
#50 ·
First: Keep your car's drivetrain clean and in tune. It can't be efficient otherwise. Use at least mid-grade fuel. I've seen negligible difference between 89 and 91/93 in my '13 LT stick shift, but 87 to 89 is such a difference I never run regular in my car. Boost your tires closer to the max. sidewall pressure - I run my 44 PSI tires at 40-44, rather than the 36/32? recommended on the door sticker. (Note: Under those pressures my original Firestones lasted exactly 50,000 miles, wore perfectly even within .040" or less across the width of all four tires, and helped the car exceed the factory MPG ratings more than a few times.) Be aware of what shape your oil, spark plugs, air cleaner, etc. are in, and if you observe sludge or carbon in the engine or intake do what you can to clean it out. Run a good fuel cleaner through it occasionally (I use Seafoam every 10K, used Amsoil PI last time). And most importantly, learn driving habits that promote economy. Gradual increases and decreases of the accelerator and brakes. Don't cram the gas into the floor out of a light, only to back off once you get up to speed - ease into it only what's needed to gain speed. Others have done more R&D on the intake resonator mod than I have - I currently have the rubber "boot" off of mine but the plastic pipe in; I figure it'll give the air an easier path when vacuum increases but help prevent the junk that gets in the fender cavity from being sucked into the intake.

That's my humble opinion on "easy/cheap" without getting too carried away.
 
#51 ·
Don't cram the gas into the floor out of a light, only to back off once you get up to speed - ease into it only what's needed to gain speed.
Excess speed is wasteful, but I'm not so sure as gentle is all that economical.

It's counter-intuitive, but sometime more power for a short burst is more energy efficient then using less power but longer. I'd suggest that the shorter the distance in lower gears, the more efficient you'll be. And that translates to a pretty brisk clip.

Why does higher acceleration minimize a car's fuel consumption?
 
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