CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

MPG Hacks, Please?

What are some legit ways to boost your fuel mileage? Tuners, k&n filter, cold air induction, porting, non ethanol gas? What say ye? We live in the sticks and our monthly gas bill is getting hefty.

Nothing will make much of a difference with a Suburban (had one for 12 years). Make sure the tires are at the sticker pressure first thing in the morning (I add 2 psi or so), make sure the front end is aligned, make sure the spark plugs and wires are good (my wires went bad). Do you need it? Something smaller would be the one sure way to get better mpgs.

What mpgs do you get?

2 Likes

You drive a Suburban? Nothing is going to provide significant mileage improvement.

1 Like

If this is the Suburban with 300000 miles none of those things you listed will help. Assuming you solved your overheating problem do a web search for hypermiling and you might find some driving tips to gain a couple of miles per gallon.

The only way to get good mileage with a Suburban is get rid of it. Sorry but that’s the only way I know.

3 Likes

Yep. Need it for work and hauling six kids and a wife. 95% highway miles. 16mpg.

Keep up with maintenance/tune ups. Use stock tire size, not off road tires. Drive slower.
The performance add-ons don’t really do anything.

Do those types of hacks work well on truck mpg? I drive 3x as much as my wife so she could take the suburban and I could “downgrade” to a truck.

Good recommendations.
Aftermarket performance mods are never successful for improved mileage, and often cause problems. K&N Cold Air Induction systems (CAI) in particular. These use oiled filters that can foul Mass Airflow Sensors (often called “MAF sensors”), as well as screw up the metering of the fuel. The ECU calculates the total airflow based on a “sample” provided by the MAF sensor, and changing the total amount of air going through the induction system without changing the calculation can throw off the metering.

“Porting”, otherwise described as opening up the passageways through which the intake and exhaust valves breath (the “ports”) is a machining operation on the heads, definitely not cost-effective for your purposes. And since the ports are probably not the greatest restriction in the engine’s breathing, I seriously doubt if it would help mileage. Engine breathing is far, far better designed these days than it was in the '50s and '60s.

Perhaps a second vehicle of high mileage for those times when you don’t need a giant rolling brick should be considered. There are some great high-mileage vehicles on the market these days.

Don’t idle to warm up engine.
Run the tires 5 psi over the door sticker.
Use a 10 deg higher thermostat.
Drive slower.

I lost 2 mpg when I switched from Michelen to another brand, did not get it back when I switched back to Michelins, the original model of Michelins was no longer being made. Maybe some tire research could get you a couple mpg.

Combustion temperatures are a delicate balance between being high enough to create complete combustion and not so high as to create excessive nitrous oxides (NOx) or unwanted combustion (pinging or knocking). The cooling system temperature is a variable in what controls those combustion temps. Raising the cooling system’s thermostat could easily push things over the desired temp and even cause engine damage. I recommend against this.

4 Likes

Non-ethanol gasoline can give a measurable increase in MPG, but its greater price per gallon may mean no savings. You’d have to calculate after running a few tankfuls.

Tires do vary in their rolling resistance, so look at that factor when buying new ones. Consumer Reports and tirerack provide data. Stay with steel wheels and OEM size tires.

Driving habits and eliminating unneeded weight and wind resistance are in your control with no upfront cost.

Many newer cars use 0W20 or 5W20 oil where in past models 10W30 or heavier were specified. For my 1999 Honda, they now recommend 5W20 even though it wasn’t around when the car was new. You may get a very slight MPG improvement with a lower viscosity oil, especially if you have been running with 10W30 or 20W50. Check with your carmaker to see if they retroactively OK a lower viscosity oil for your engine.

Suburban - giant box on wheels - heavy - how would one have control over wind resistance on this thing?

1 Like

How fast you drive is the main way to control wind resistance. If you go half as fast, wind resistance force is only one quarter as much.
You have to accelerate the mass of the vehicle to its cruising speed and if the cruising speed is only half as much, it only takes one quarter the energy to accelerate the vehicle.
Where most people really waste fuel is in accelerating to cruise speed over and over again because they have this compulsion to race towards the next red light. Stop accelerating and let the car coast and that same light might turn green before you reach it.
Drive as if your brakes don’t work and you’ll get amazing gas mileage.

Changing your driving habits will add more mpg than any modification you do to the engine.
Free flow air filters and exhaust have no practical effect when the main bottleneck to airflow is a partially open throttle which you can’t avoid unless you want to go to jail for speeding or die in a crash.

2 Likes

What do you mean by this?

If you have a 180 degree now replace it with 190 is what that means. I am with Mr. Mountainbike, I would not do that. I seriously doubt you would gain enough MPG to even notice.

1 Like

BLE is entirely correct, follow his recommendations.

I could add:
use cruise control, which causes you to move at a constant speed. Keep that speed as low as you can tolerate.

Roof racks decrease MPG a lot

Keep a good distance between you and the car ahead of you. This minimizes fast stops and allows a more constant speed.

1 Like

I don’t think a 190 vs 180 thermostat can do any damage when coolant temp can reach 220 under certain conditions.
We’ll just have to agree to disagree.
My '81 Accord had two thermostat options from Honda.
The trade off of a hotter thermostat is a slight loss of power.

I would get wrid of the Suburban and get a used mini-van. A Dodge grand-caravan comes to mind .