How can I improve my car's fuel economy?
 

I drive a 1995 Toyota Avalon. I have installed iridium spark plugs, installed a K&N air filter, used Chevron Techron Fuel Injector cleaner (with the most recent usage being two tanks ago), accelerated moderately, driven at the speed limit, coasted to red lights, keep extensive fuel economy records since early this year, determined a brand of gasoline that my Avalon burns the most efficiently, filled my tires 2 psi higher than Toyota's specification, used 5w-30 Castro GTX motor oil (I have so many quarts of it that I have a mini oil reserve in my home) and kept the windows up. My Avalon used to average 25.5 mpg without the air conditioner, but since I switched to another brand of gasoline and the temperatures started rising, both mid-last month, my Avalon has averaged 26.9 mpg with the air conditioner. I commute to and from my college each day, with my mother with me because she needs to use the car while I am in school, therefore commuting from and to my college each day. Half of the commute is on roads without lights and 55 mph speed limits and half of it is on roads with some lights and 55 mph speed limits, only at the very beginning and at the very end are the conditions different.

What can I do to improve my Avalon's fuel economy?

Few misconceptions you may be interested in: Iridium spark plugs don't help gas mileage. Iridium is less conductive than copper, and are worse than cheap copper plugs. They just last a long time. Its not likely to make a difference in fuel economy or performance though unless you were using them in a supercharged or turbocharged engine. Some cars develop a slight miss with iridium or platinum plugs. Fuel injector cleaner usually doesn't do ****.

To clean your injectors you need to buy an injector o ring and filter kit, take out you injectors, take out the filter inside them, let them soak in a blend of diesel fuel, seafoam, and other nasty cleaning stuff you don't want to touch, and the gunk will get out of them. Install new filter and O rings. Good as new! To be sure you can get them flow tested by Mr. Injector on eBay.

I just made a new best and worst mods list. Check out that one for more info on what you can do.

Welcome to GasSavers!

Take a look at the Busted/Confirmed Mods section as tested by our long-standing members.

To clean the intake/combustion areas, Seafoam, AutoRX, or even a little water into the brake booster line will steam clean the carbon and should clean injectors.

Take a look around, and feel free to ask us any questions -- we're here to help :thumbup:


Best FE,

RH77

The Iridium spark plugs that I have (Denso IK20) are only rated to last 30,000 miles, which is worse than nickel spark plugs. At clublexus.com, there are quite a few people driving cars with the same engine as mine that find torquemaster spark plugs give them more horsepower and torque in dynometer tests, so I will be using those when it is time to replace my spark plugs on the assumption that they do that by producing a leaner burn.

Taking out my fuel injectors is impossible for me because of the design of my Avalon's engine, so adding additional detergents to my car's gasoline tank every now and then is the best that I can do the clean them. On the bright side, gasoline is a solvent and most fuel injector cleaners are solvent based, so while most fuel injector cleaners do absolutely nothing, the few detergent based fuel injector cleaners on the market, like Chevron Techron, do something, most likely because most major gasoline brands do not contain enough detergents in their additive packs as a result of federal standards (see www.toptiergas.com). I have always seen a boost in fuel economy for several tanks after adding Chevron Techron Fuel Injector cleaner to my tank. Then when it starts to drop I add it again, gaining the same boost.

As for the mods list, I will take a look at it; thanks.

I forgot to mention that I have already run an Auto-RX treatment through my engine. I have also had my engine resealed (before running the Auto-RX treatment) because it was leaking (I ran Mobil 1 through an engine that had bad seals).

I will take a look at the mods section. Thanks.

How many miles are on the engine and are you doing the Auto-RX on a regular bases? Is that engine prone to sludge and did the Auto-RX work for you?

Welcome to the site it looks like you're headed in the right direction.

The engine has 98,625 miles on it, give or take three miles (I would have to go outside to get the exact figure). The engine was produced two years before the engines with the sludge problems started to be produced, so while many other 1MZ-FE engines are prone to sludge, it is not. As for the Auto-RX, I ran one treatment at 93,493 miles, with the rinse phase stopping almost a thousand miles late around 97,800. It did not improve my fuel economy significantly, but there was a small gain.

Edit: I was reading through the modifications section and I came across something about low rolling resistance tires. My car currently has Pirelli P400 Touring All Season tires. Do these have low rolling resistance?

Is your commute hilly at all or is it dead flat?

There are some hills, but it is mostly flat with some bends in the road. The only hills I encounter are at the very beginning and at the tail end.

+1 For using an Fuel injecter cleaner. Berimans B12 helps make crisp low throttle drivability and gas milage. Used to use "super contrentrated" STP FI cleaner too. But only as nessary (every year or so?) It helps when you use Less than top tier gas.

Manufacturers haven't been very forthcoming with rolling resistance specs for their tires. There was a report that came out about four years ago now - but most tire model names have been changed since then, and the ones that haven't had their names changed have likely been redesigned anyway.

Personally I've given up on finding actual rolling resistance specs.

HOWEVER I've been ignoring my car maker's recommended pressures, and inflating to "max sidewall" instead. That is, the max pressure stated on the sidewall of the tire.

I'd recommend ignoring the car maker's suggestion and use max sidewall. Check the "Best & Worst Mods" lists for any other comments on that.

Since tires will gain about 4 psi when hot from driving, check pressure before the first drive of the day, when still cold. Tire design + construction is able to take the increase as it is driven. I usually end up guesstimating when pumping up (because the tires are already hot) and then let off a bit the next morning if needed.

And don't use the absolute cheapest pressure gauge either. I eventually got a nice $15 brass mechanical dial gauge from a real parts store (not a big box store). It's supposedly accurate to +/- 1 pound. The others don't even say how accurate they are... But I'm rambling. Point is, if you're going to set tires to the max possible you better be trusting an accurate gauge, not one that gets slammed on the ground by other users.