Really Crappy Gas Mileage - ideas??

[MrMikeL]

Hello all,

I recently completed a 2,238 mile trip from Minneapolis to Madison, Chicago, St. Louis, Kansas City, Des Moines, Chicago, and back through Madison to Minneapolis. Since this was mostly highway driving, I assumed I'd be getting around 29, 30, 31 MPG. I have experienced that mileage in highway driving in the past. I don't use the computer to tell me the MPG, I calculate it the old fashioned way (more reliable).

Imagine my horror when the best highway mileage I got was 26! My son, on a learners permis, was driving very conservatively (slow) and I tended to be a bit more heavy pedaled, and there still was no difference.

So I started thinking about what could be causing the bad mileage. I checked the tires - they were to spec all along the trip. The car only has 31k miles, so I don't think it needs a tune-up. I serviced the K&N filter about 6 months ago, so it can't be that dirty yet. I will admit to blasting the A/C along the way, but I always thought that A/C only accounted for a 1 to 2 MPG loss.

I have a 2004 V6 SLE convertible, and the top was up all the way because of the hot & humid weather. Can anyone give me some ideas? Is it time to take it to the dealer for diagnostics? The car runs great otherwise.

Hey, thanks in advance for all responses!

[Somedude]

using the A/C while driving can worsen the gas milage by 2-5 mpg, not 1-2 mpg.

You say you are a lead foot, that is also another reason why you get crappy gas milage.

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When I am driving my Solara, I rarely push the car past 3000 rpm let alone at 3000 rpm. I use the A/C occasionally and I still get 27-30 mpg per tank.

[steve-o]

I have 4 cyl/5-spd manual - I get around 30mpg highway, w/the A/C on and mixed in with a few stop and go miles around 28 or a bit less. IMHO w the 6 cyl. your doing good with 26 A/C on. These milages are with no passengers or added weight in the trunk.

[Somedude]

I don't know if you done this but make sure to change your car's engine oil every 5000 miles for better performance and longer engine life.


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My brother has a 2003 Honda Accord V6 w/Auto and he gets 26 mpg per tank. The car is well maintained.

[MrMikeL]

Engine oil changed regularly every 3k miles. Lead foot or not, my mileage is always consistent. Even with A/C, used to be about 30 MPG on highway.

Any other ideas??

[Somedude]

what kind of engine oil do you use? 10w-30 or 5w-30?


26 mpg is not too bad for a V6. My gas milage these days are not as good, maybe it is because of the heat and humidity. I get better gas milage when it is around 70s or low 80s.

[CosmicGrooves]

Did you clear the mpg before the trip?

On a 3hr drive, I got 35mpg a few weeks ago. I thought that was pretty good for the V6!

That was with cruise control and AC!

[Mayor]

I have a 2004 SLE V6 Convt too - so here are a few things to increase your mileage:

1) Check your tire preasure - make sure they are ALL the same and all are around 38 to 40 PSI. If you have the standard 17" tire - the max PSI is 42. Low or different tire preasure is a SURE way to get crappy gas mileage.

2) Cruise Control is your friend. I drive 72 miles (one way) to my job every day. I did a test. I drove to work one day with Cruise Control ON at 65 MPH the whole way. I averaged 34 MPG according to my computer. The next day I drove with Cruise OFF and drove at 65MPH the whole way - and I averaged 28 MPG - HUGE difference.

3) AC will kill between 3 to 5 MPG and even MORE if your not using Cruise Control. Also, did you have a full trunk of luggage with you? If your son weighs 150 lbs + this too will lower your mileage.

4) Lead feet will KILL you. Did you know that when you change lanes quickly and you go from 65 to 70 MPH the AVERAGE car gets 9 to 11 MPG during that burst of speed? Now, on a 2 or 3 hour trip - how many times did you punch it or jump on it to change lanes??? That 9 to 11 MPG all get averaged in to your MPG total.

I hope this helps!

Mayor

[MrMikeL]

We used cruise control most of the way. And I challenge the 5 MPG that A/C chews up. Cold tire pressure, as posted in the driver door well, is 32 PSI, not 38 or 40. Heated up, a 32 PSI cold reading is 37 to 38 hot.

[PXLpainter]

4) Lead feet will KILL you. Did you know that when you change lanes quickly and you go from 65 to 70 MPH the AVERAGE car gets 9 to 11 MPG during that burst of speed? Now, on a 2 or 3 hour trip - how many times did you punch it or jump on it to change lanes??? That 9 to 11 MPG all get averaged in to your MPG total.

Is THAT why I only get 9-11 mpg per tank these days?

[Turbosolara]

did you use premium fuel? and did you clear up the trip computer before the trip?

[MrMikeL]

I always use premium. And I never pay attention to the on-board computer. I calculate my MPG on miles travelled since the last fill-up and number of gallons purchased this fill-up. Like I said at the beginning, I never use the 'puter, I always calculate it the old fashined way.

As for oil, I always use the appropriate weight for the weather and I always change it every 3,000 miles or every 3 months, which ever comes first.

[kamikazi]

u should have drop by and said hi to me in Des Moines

[Turbosolara]

actually it is bad to serve your k&N filter too much, the filter oil will dirt your MAF sensor, throttle body, and intake maniford.

how is your alightment btw

[Mayor]

You dont use the DOOR sticker to gauge your Tire preasure. Look ON the tire and as I said, if you have the standare 17" tire, the max PSI is 42. If you DONT have the standare tire, then again, look ON the tire.

So if you are running 32 PSI on tires that have a MAX of 42 - that will explain why your mileage is so horrible. The back profile of your tires probably look like a bag of coins on a flat surface - much harder to spin them and directly affects your mileage.

Thanks,

Mayor