'99 Gt

Lando454 · Nov 4, 2017

Hey do you guys have any ideas on getting better gas millage in my 1999 GT? The V8 just sucks gas!

Noobz347 · Nov 4, 2017

What's your mileage now?

Lando454 · Nov 5, 2017

Noobz347 said:
What's your mileage now?

Oh boy couldnt tell ya... I am going to do a fuel system cleaner to hopefully help a little. I dont think I am used to driving a V8 yet so the gas part is had to get used to lol

Ronin38 · Nov 5, 2017

Check your tire pressures, too. Adding just 2 psi over the recommended pressure can help, without causing other issues.
Are your air intake and exhaust in good condition? The engine needs to breathe properly to be most efficient. Also, try to be gentle (I know!) with the throttle in normal driving.

Noobz347 · Nov 5, 2017

Lando454 said:
Oh boy couldnt tell ya... I am going to do a fuel system cleaner to hopefully help a little. I dont think I am used to driving a V8 yet so the gas part is had to get used to lol

Don't waste your money on any snake oil products. Let's begin at the beginning.

Tell us what method you are going to use to get your initial calculation for fuel mileage so you can share that with us.

IIGood · Nov 5, 2017

For reference, my 2003 GT (which has the same 4.6 V8 as your '99 GT) with manual transmission gets about 19-20 MPG in mixed driving. My tire pressures are at 35 psi and the engine is all stock. Air & fuel filters are changed regularly...well, the fuel filter is a little overdue at the moment, but still.

There was one time...just one time...that I ran a whole tank on all highway driving and pulled 30 MPG out of that. I couldn't believe it myself and did the math a couple times...it all checked out. But that was just once. I really don't do much of any all-highway driving, it's all mixed now...it's mostly just my commuter back and forth to work on nice days now that I have a second vehicle.

But yes, as others have requested, let us know what your routine is now. How will you calculate your MPG? Is it a manual or automatic? What size wheels are on the car (if they aren't stock)? What are your tire pressures like? How do filters look? Are there any modifications to the car?

Oh, and is it a coupe or a convertible?

Lando454 · Nov 5, 2017

Its an automatic 4-speed coupe with a K&N cold air intake with a recently cleaned filter and FlowMaster super 44 mufflers. The tires are 245/45R17 99W by Fuzion

Lando454 · Nov 5, 2017

https://www.amazon.com/gp/product/B000CPI5Z0/?tag=stangnet-20

Even if it helps or not I need this.

IIGood · Nov 5, 2017

Lando454 said:
Its an automatic 4-speed coupe with a K&N cold air intake with a recently cleaned filter and FlowMaster super 44 mufflers. The tires are 245/45R17 99W by Fuzion

Okay, now that we have the car specs established, what is your current gas mileage and how are you calculating It?

An automatic will most likely get slightly lower gas mileage than a manual so there's one impact.

Lando454 · Nov 5, 2017

My buddy that owned it said he still was getting the normal MPG (17) but I dont know how he calculated it... We have drove the car together for the past 8-9 years

IIGood · Nov 6, 2017

Lando454 said:
My buddy that owned it said he still was getting the normal MPG (17) but I dont know how he calculated it... We have drove the car together for the past 8-9 years

17 doesn't sound too far off from what it should be. Check the tire pressures and be sure they are set to at least 35 PSI when cold. And then do this to calculate the average MPG:

- Completely fill the tank
- Before pulling away from the pump, either reset the Trip Odometer to zero, or write down the overall mileage showing on the odometer
- Drive the car as you normally would until the tank runs out
- Completely fill the tank again and this time, note how much fuel went into the tank...right down to the last thousandth of a gallon (e.g., 12.875 gallons)
- Look at either the Trip Odometer and see how many miles it registered since the previous fill, or subtract the last fill's overall odometer reading from this fill's overall odometer reading
- Divide the miles you drove by the amount of fuel you put in the tank on the second fill; example: 250 miles / 12.875 gallons. This will produce your average MPG for that tank.

Lando454 · Nov 6, 2017

I will have to do that! I have my tires at 35 PSI but I noticed when I was checking them when I made the post that they max at 50 PSI...

IIGood · Nov 6, 2017

Lando454 said:
I will have to do that! I have my tires at 35 PSI but I noticed when I was checking them when I made the post that they max at 50 PSI...

No, leave them at 35. Overinflation like that can cause uneven wear and worse, like loss of control. You can add an extra pound or two to help.

It really just sounds like 17 is normal.

Ronin38 · Nov 6, 2017

When I upgraded the tires/wheels on my other car from 18's to 20's, I knew the door sticker at 35 psi was not valid any more. That is only for the stock size wheels and tires. I started at 35 psi (ride felt "mushy" and steering took more effort), and slowly worked my way up to 45 psi (ride was bouncy and harsh, steering felt very light, car rode "skittish" on the highway), I eventually got it narrowed down to 40 psi. That worked very well, tread wear was good, too.

General karthief · Nov 7, 2017

Another thing is tire size matching with the speedometer, gear ratio, speedometer gear in transmission all have to work together to give accurate mpg readings, see how accurate you odometer is by doing 60 mph and match the mile markers on the highway or stop watch, 60 mph is one mile a minute so check you numbers.

Mustang5L5 · Nov 15, 2017

Lando454 said:
I will have to do that! I have my tires at 35 PSI but I noticed when I was checking them when I made the post that they max at 50 PSI...

Go by the door sticker which takes into account tire contact patch surface area and weight on each tire for recommended tire pressure. Tires just list a MAX pressure they can safely be inflated to, but since they can be mounted on many different vehicles, the recommended pressure will vary.

Of course this goes out the window when you change tires or tire sizes. If you go with wider tires with bigger contact patches, you can typically reduce pressure.

Anyway, sounds like your MPG is really average depending on your driving style. I remember my 2003GT used to average 25-27MPG highway, but in town with shifting 17-20 was typical. You really need to drive the car like you have an egg between the gas pedal and your foot to get good mileage. If you want better gas mileage, time to buy a different car.

Noobz347 · Nov 15, 2017

Lando454 said:
Amazon product ASIN B000CPI5Z0View: https://www.amazon.com/gp/product/B000CPI5Z0/?tag=stangnet-20

Even if it helps or not I need this.

Snake oil.

Red_LX · Nov 18, 2017

Since I did my cams I only average 16 mpg in mixed driving and I don't even care. Still gets mid 20's on the highway though. I can deal with it to have a V8.

'99 Gt

Lando454

New Member

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Lando454

New Member

Ronin38

Blow all the things!

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

IIGood

Lando454

New Member

Lando454

New Member

IIGood

Lando454

New Member

IIGood

Lando454

New Member

IIGood

Ronin38

Blow all the things!

General karthief

wonder how much it would cost to ship you a pair

Mustang5L5

That is…until I whipped out my Bissell

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor

Red_LX

I’m not much help unless you’re looking for ****!

'99 Gt

New Member

Stangnet Facilities Maint Tech... Er... Janitor

New Member

Blow all the things!

Stangnet Facilities Maint Tech... Er... Janitor

New Member

New Member

New Member

New Member

Blow all the things!

wonder how much it would cost to ship you a pair

That is…until I whipped out my Bissell

Stangnet Facilities Maint Tech... Er... Janitor

I’m not much help unless you’re looking for ****!

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