Not as good as I hoped

[Angelus359]

I did a upper grillblock which seems to help with warmup time, filled my tires to 44psi, and drove very gently, accellerating slowly, and coasting down to lights when I can.

I drive mostly cityish which is the problem. Its not hardcore city, but by no means what so ever is it highway.
I have a 2008 chevy aveo automatic with 35k miles on it. Its EPA estimates are 23, 32 (26combined).

I just did a tank at 28mpg. The temperature has been 29 to 65 averaging around 45 for the duration of that tank.

What can I do as a significantly financially strapped college student? I don't think aero will help terribly much because I almost never drive above 45mph, and rarely above 35mph.

Oil is fresh dino oil, 5w30, though my trans fluid isn't super pretty.

As its 21% over EPA for city, what else can I do?

I like having a spare tire.

[bestclimb]

No worries about ditching the spare, it is a pretty insignificant weight compared to the rest of the vehicle.

The automatic in the AVIO I rented was horrendous, downshifting at the slightest provocation, staying down far to long.

Does yours have instantaneous fuel consumption readout? If not MPGuino, scan gauge or the like may be a great help for you. It will really help refine your technique. I guess my MPGuino is worth about half of my improvement in the Civic, which means it has paid for itself more than 4 times over in the last year.

About the best I can offer for technique at this point is learn where the thing down shifts, then don't push the gas down to that point while accelerating, push it down just to that point to get the throttle opened up a bit. When getting close to a shift point you can lift up a bit and cause the car to shift up and then resume accelerating at the throttle position just before it downshifts again.

[saand]

hi angelus,
i have an auto as well which makes it difficult to get the gains you will see people with manuals are getting.
if you want ideas on what you can do there is the wiki also if you look at my cars profile bugler, i have listed what my modifications are. They are all very cheap, i dont think i have spent more than 50 dollars on all of the mods however i have "borrowed" parts from work occasionally.

A quick and easy modification you may not have considered or you may have considered and dismissed is shifting into neutral and do pulse and glide. you mention you coast down to lights but do you do it in neutral. I found at least with my car that coasting in neutral to lights and doing general pulse and glide i got a large improvement maybe 12% (number plucked out of the air)

also turning your idle down is an easy change and gives some small gains which are increased if you go into neutral when going toward lights.

it may not have crossed your mind but you might be able to sell your car, get a manual that starts off with high MPG. You might break even doing that depending on what car you have.

well good luck

[Angelus359]

My car is damn near perfect mechanical condition, as I bought it used a bit ago, it was still under warranty, and then I had a mechanic friend go up and down over the whole thing checking it out, which then I had a dealer fix under warranty.

I'm not going to sell that. As is, I spend 15 dollars a week on gas.

Can re-engaging the transmission from neutral, while moving, be damaging to the auto transmission? Often I'll start coast down to a light, and then before I get there, it turns green again. There are a LOT of lights around here (every 2-4 blocks on all major roads, and all side roads have stopsign every block).

I live on the southern edge of chicago.

I think maybe the temperature is coming into play a bit.
Lots of short drives. I rarely drive more than 6 miles.

[MetroMPG]

All else being equal, cold temps will definitely drag down your MPG.

You could address that somewhat with a block heater and synthetic engine oil (more stable viscosity than dino, so less of a warm-up hit at start-up).

Do you have instrumentation?

Also: look up user Thymeclock. He's got an Aveo automatic, and knows quite a bit about the operation of the transmission. I believe he'll tell you getting good MPG in the city below a certain speed (before the torque converter locks) is particularly challenging in this car.

[Angelus359]

The manufacturer recommends 0w 30 or 5w 30 oil.

I think I'll buy some synth 0w30 when I need a change. Do it myself.

Once I acquire a new job I'll buy a scangauge...

[Angelus359]

My trans fluid is a bit dirty, but not horribly. Would synth be much better there?

[IsaacCarlson]

maybe a TC (torque converter) lockup switch is in your future?

[Thymeclock]

Originally Posted by Angelus359

Can re-engaging the transmission from neutral, while moving, be damaging to the auto transmission? Often I'll start coast down to a light, and then before I get there, it turns green again. There are a LOT of lights around here (every 2-4 blocks on all major roads, and all side roads have stopsign every block).

I live on the southern edge of chicago.

I think maybe the temperature is coming into play a bit.
Lots of short drives. I rarely drive more than 6 miles.

I have an '09 Aveo5 and have the same stop sign and traffic lights situation as you do with the city MPG being lousy, especially for such a small car.

You might find this thread of interest: click here.

Poor city gas mileage is entirely due to the way the automatic transmission is programmed. Mine gets excellent FE on the highway (37 MPG) but only about 21-22 in the city. I bought it as a commuter car for my wife and the driving done with it is entirely city driving. Frankly, I think that GM fudged EPA stats for city MPG.

I would not recommend re-engaging the A/T from neutral into drive while moving. The car will not know what gear to go into, and probably will go into a lower gear than appropriate. I once burned out the clutches on an A/T by doing this and having a tranny rebuilt is a very expensive proposition. Go to an independent transmission repair shop and ask them this question. They will advise against it.

However, what you can do safely is to throw it into neutral and coast when approaching a stop sign. You will need to stop anyway, and when you put it back into drive it will go into first gear - which is OK as long as you are moving at less than 10 MPH.

Another strategy that helps is to accelerate briskly to get into the highest gear possible, as quickly as possible, then keep your foot off the gas as much as possible except to keep it at speed for whatever the highest gear it is in. The lower gears really consume fuel. The shift points are at about 12, 25 and 32 MPH, respectively. But the 'holy grail' magic number is 45 MPH, as that is when the torque converter locks up and the FE increases dramatically. On most cars this occurs at about 40 MPH, and Chevy really messed up in making the lockup occur so late. Unfortunately there is no way to change it. That's how they get 37 MPG highway: the speed must be more than 45 MPH. But there is no way you will get anywhere near that much in city driving, even if you are going 30 or 40 MPH.

[Thymeclock]

Originally Posted by Angelus359

My trans fluid is a bit dirty, but not horribly. Would synth be much better there?

I'd say drain it (or also drop the pan and check the filter) and change the fluid. (You won't get all the fluid out but if you change the fluid once or twice a year it will improve its condition - like doing a transfusion.) Tranny fluid that becomes deteriorated can cause transmission failure. There is no real advantage to synthetic fluid - ordinary (but clean) fluid will do fine. All the Aveos use Dexron III fluid, which is inexpensive.