2009 Chevy Cobalt LS Coupe XFE

[MadisonMPG]

Good job. (makes me want a Cobalt even more)

[Fr3AkAzOiD]

You should start a gas log here Jammer.
It really helps motivate you and notice trends and improvements over time.

[ALS]

Originally Posted by Jammer

Until I get around to my first oil change I think this is about the best mileage I can get. It's 2 tenths higher than before, and that is with a lot of use of EOC. I really feel I'll be able to break 50MPG once I get the break-in oil out of the engine, which is due within a couple of weeks.

It sure beats the regular Cobalt at EPA 33 Highway.

I realize this car can do better, and I will get 50MPG plus or die trying.

At about 5K miles you should start to see a jump in fuel mileage. Don't expect to see your top fuel mileage until after 10K miles. By then your engine and transmission should be pretty much fully broken in.

[Nevyn]

What kind of mileage are you XFE guys seeing on a cold engine? I just took one for a spin and was impressed AND disapointed. 54 degrees F outside; completely cold car, 7.4 miles, 34.7 MPG. Good, but I was hoping for 37 from cold. Was I too "gentle" in my hypermiling, or is that a decent return?

I have two cars that are both dying; I fear one will keel over this winter for good. So I'm weighing options.

[Jammer]

Originally Posted by Nevyn

What kind of mileage are you XFE guys seeing on a cold engine? I just took one for a spin and was impressed AND disapointed. 54 degrees F outside; completely cold car, 7.4 miles, 34.7 MPG. Good, but I was hoping for 37 from cold. Was I too "gentle" in my hypermiling, or is that a decent return?

I have two cars that are both dying; I fear one will keel over this winter for good. So I'm weighing options.

Tire Pressure / Battery

(My first thought is it may be your gas- see next paragraph)

It has dropped down to 40 degrees here during some of my short test runs trying to improve my driving in EOC. I'm still holding steady at 45.4MPG- However I noticed my tire pressure dropped when it got cold and that can explain some lost MPG. I now try to keep my tires at 40PPSI - they hold 44 MAX, so I figure 40 would give me some head way during warmer days and longer drives in which the tire pressure goes up. GM claims 30ppsi for the tires, but raising it sure does help the mileage and the outside temps directly impact the tires and the battery in the trunk. My problem is I have too much power drain running with brights on, along with all of my car's toys like cb radio, radar detector and GPS and even MORE- thus driving half as much in EOC is creating a situation in which my battery is cold and not holding a charge like a warm battery would in an engine compartment running full time. I plan on taking some advise on here and duct tape some home insulation on the bottom and sides of my battery.

Gasoline:

They mix gasoline ahead of the dates it gets pumped into cars and they try to formulate gas so it will burn it's best at the EXPECTED TEMPERATURES FOR THE TIME OF YEAR YOU FILL UP. Sometimes they screw up, and a summer may be fairly cool and the gas is mixed for hot temps which results in poor MPG. The same applies in reverse, if it is getting colder much earlier in the year than average your gasoline may be formulated to burn it's best at a higher temp. (I am basing this information on what many people have told me for years, but if anyone else has information on this stuff please share it here.)

[salty9]

Odometer MPG increases with tire wear due to 2 reasons one of which is illusionary. As the tread is worn away the tire has less rolling resistance (more MPG). The circumference is also decreased which leads to more tire revolutions per mile and higher indicated MPG. I noticed this when I had new tires installed.

[cfg83]

salty9 -

Originally Posted by salty9

Odometer MPG increases with tire wear due to 2 reasons one of which is illusionary. As the tread is worn away the tire has less rolling resistance (more MPG). The circumference is also decreased which leads to more tire revolutions per mile and higher indicated MPG. I noticed this when I had new tires installed.

Yup, that's why I do a GPS/Odometer correction check every 6 months or so.

CarloSW2

[Jammer]

Originally Posted by cfg83

salty9 -



Yup, that's why I do a GPS/Odometer correction check every 6 months or so.

CarloSW2

Interesting, you just sparked a light bulb here. I had noted that when my car was being driven within it's first two weeks that my GPS read a faster speed than my Odometer read. This really bothered me because with my previous Colorado pickup truck the GPS AND the odometer were in 100% agreement on the speed I was going.

Now after all of these weeks since the day I purchased my XFE Cobalt I notice my GPS and odometer are back in sync with each other, they both display the exact same speed. I wonder if 4,000 miles is enough wear on the tires to explain this? I can not detect any wear on my tires as of yet- it seems to be a really hard rubber compound they make these types of tires with.

Speaking of TIRES:

This is a 1986 Pontiac Fiero GT with after-market wheels and tires. I owned a 1985 and the stock wheels and tires were not as nice to look at. The body was made of PLASTIC!

I was reminded the days of my youth when I saved up a large down payment and got my dream car of 1985- A Pontiac Fiero GT. The Eagle GT Radials were stock, and boy did they wear out FAST! But, the car could take corners as good as a Corvette. It was very fun to drive. EPA MPG was something like 25 and LOWER- it had a Buick made V-6 in the rear of the car, and the engineers caught a lot of heat for placing a 3 quart oil pan on this engine which lead to hundreds of car-fires (It needed a 4-5 quart pan that was too large for the space the car had). GM ended up paying dearly for such an obvious mistake, thus the main reason that car did not stay in production very long(LAWSUITS!). It was before standard airbags hit the market, and being a plastic body, it scared many people in case of a wreck. Also only 3 of the 6 plugs were easy to replace (the engine was in the rear with enough trunk space for one handbag or purse!, the front hood was to cover the sunroof when it was removed and stored) One needed a fancy tool to reach the other 3 plugs at the bottom of the car- the best method was to have the car up in the air and then reach up and change them, it was a big issues with owners back in it's day. I think it was built for less than 5 years, but the very first year sold great for them with numbers well above 100,000 Fieros the first year. BUT, it was no fun having to replace the Good Year soft compound Eagle tires. True the tires gripped the road like a race car on dry pavement......

But the tread wore of off two sets of these tires at close to 10,000 miles each! I finally got some much harder compound tires on the beast and then it rode like a camel on a road with a earthquake fault line. But the tires had the lifespan of triple what the soft Good Years Tires were giving me. I do not care how smooth a ride is, nor how well the tires grip, I feel a set of 4 tires need NOT be replaced every 10,000 miles. I gave up some cool cornering ability in order to have tires make it another 20,000 miles before needing a change. Modern day tires have really came a long ways and are much better in every way, except maybe price.

Hmm
Thanks.

[Fr3AkAzOiD]

Originally Posted by Nevyn

What kind of mileage are you XFE guys seeing on a cold engine? I just took one for a spin and was impressed AND disapointed. 54 degrees F outside; completely cold car, 7.4 miles, 34.7 MPG. Good, but I was hoping for 37 from cold. Was I too "gentle" in my hypermiling, or is that a decent return?

I have two cars that are both dying; I fear one will keel over this winter for good. So I'm weighing options.

I ran 36/37 mpg all last winter and I wasn't hypermiling. Granted my tires were at around 34/36 psi but most of the time I was doing 65 mph in a 55 (shame on me). I'm sure that depending on your route and how much snow you get where you are you could easily get 37 or better.

I myself am really hoping to keep my 90 day averages above 44 mpg all winter.

[Jammer]

Originally Posted by Frank Lee

Driving for fe, ya won't need that radar detector any more.

Valentine One radar and laser detectors

Ah, funny you should mention that now! Guess what just happen to me a few hours ago in the daylight? A few miles up the road from here is a very large hill that is fairly steep and sort of curves on the way down. With 3 lanes it's actually one of the safest places I have found to run EOC all of the way to an intersection near where I live. The problem is IT'S EASY TO FIND YOURSELF GOING 68MPH for a few seconds as you bottom the hill, and with this speed I can make it all the way to the 4 way stop sign about 1 mile further on, and it normally works perfect. Read on....

I was driving down this hill in EOC today and had a couple cars about 1/2 a mile ahead of me moving in the same direction. I was half way down the hill in EOC and my Valentine One directional radar detector started beeping with an arrow pointing ahead of me. I was at almost 60, and could of been moving over 65MPH and drove right past that state boy's radar gun, and they WILL give people tickets here for moving ten over. Well, I had plenty of time, but hated to have to hit my brake, and was moving 53 past the state boy going uphill past me. Without that radar detector I would of been clocked at somewhere around 65 to 70-tops in a 55 zone!

So even when trying to drive in a manner to save gasoline we still have these situations when we are trying to get all of the speed we can get in the mountains in which one could get a speeding ticket cruising 70MPH or better in what is otherwise a very safe way of saving gas until we need to either stop/slow down/ or bump start. My Valentine One saved me today for sure.

In fact, this is so off topic I might post another thread about this issue.