Fuel Economy and Air Conditioning

[RiderOnTheStorm]

Hey All,

I have an 5-speed '11 Aveo LS which I had the dealer install A/C. I know that A/C tends to be parasitic, but I was curious if anyone knew by how much?

I just ran a 300 mile highway trip @ 75 mph w/ A/C 4 passengers and a cooler and got 27.5 mpg.

Today I ran a 94 mile highway trip at 64 mph w/ A/C and just myself and got 29.4 mpg.

I feel this milage is extremely low considering I had an 2.5 Altima S as a rental and I did 75 with A/C and got 32 hwy. I am just curious if this sounds right for other Aveos with A/C?

[redrob]

If its new thats part of the issue, new cars need to be "broken in" first then the MPG starts to climb. It is difficult to say how long before you will see an increase in MPG but running the A/C has little effect on overall MPG. The big thing is the speed your driving at( 65, 75, 85mph) and you will see your MPG drop significantly. Also dropping the added weight will also help improve your MPG. All in all your new car will not get your EPA estimated MPG at the begining. I have an 08 hatch (auto running A/C) I get about 315 miles out of the tank so I still need to figure it out but its around 28-30mpg at 65-75 with big elevation changes.

[RiderOnTheStorm]

Thanks for the reply redrob! I have ~1000 miles on her, so I am passed GM's break-in period, but I had heard that initial mileage is usually not so good. Usually when would one see improvements?

[petrified.rabbit]

with the windows down, 80-85 mph, mostly highway (>80%) I got 32 mpg with my last tank.

the '11 has a slightly taller 5th gear, so you should be able to do better.

ac does take up to 15-20 hp.. on a bigger engines its less of a drain.. keep in mind there are a lot of factor to fuel economy than just engine size, epa estimates, etc.

[paulsaveo]

I lose about 2 mpg when I use my a/c. I average 320 miles for 10 gallons, when I use the a/c i get roughly 295 for 10 gallons

[Thymeclock]

If its new thats part of the issue, new cars need to be "broken in" first then the MPG starts to climb.

I've heard this nonsense repeated before, but never is there any proof offered. It sounds like something a dealer would say to get you to go away and stop complaining. Please explain how and when this magical event of "then the MPG starts to climb" is supposed to occur.

[Thymeclock]

My test, conducted using a ScanGauge when the car was still practically new, recorded 37 MPG @ 65 MPH with the A/C on, on a level highway, determined over a 20 mile trip. As soon as the speeds are lower than 50 MPH (owing to the A/T not being in lockup mode) the MPG drops enormously.

This car gets wonderful MPG if you can always drive exclusively at highway speeds of over 50 MPH and avoid all other types of driving.

And as for the "broken in" myth, now that my car has 8000 miles on it the MPG is still the same as the day it was bought new.

[RiderOnTheStorm]

I lose about 2 mpg when I use my a/c. I average 320 miles for 10 gallons, when I use the a/c i get roughly 295 for 10 gallons

Your milage sounds fairly close to mine so I feel a bit better seeing that - thank you! What speeds are you typically driving?

[RiderOnTheStorm]

...ac does take up to 15-20 hp.. on a bigger engines its less of a drain.. keep in mind there are a lot of factor to fuel economy than just engine size, epa estimates, etc.

If what you're saying is true, that could be up to a 20% performance loss on this vehicle which would take 35 mpg down to 28 so that makes sense.

[redrob]

I've heard this nonsense repeated before, but never is there any proof offered. It sounds like something a dealer would say to get you to go away and stop complaining. Please explain how and when this magical event of "then the MPG starts to climb" is supposed to occur.

Its nothing that I have gone into researching.............its just something that I have heard as well. When I would get a new car it wasnt to save gas so I wouldnt check to see what my MPG was and when I bought this car (to save gas) it was used. I do remember there being some rumors about engine shavings and impurities in the oil for a new engine but I dont know if that affected MPG or if it is even true( again I dont care enough to go do some scientific research) to begin with. BTW do yoou have any info other than your experience that confirms that this "myth" is just that or do you just say this casually?