Sonic 1.8L LTZ issues

[shovey]

I bought this car at Jerry's in Leesburg, Va as a left over model last march (2014) and I have NEVER gotten anywhere close to any of the posted fuel mileage on it. My trips to work are 80% highway. I haven't even gotten 300 miles out of a tank. When I fill up at the first pump cutoff, I average 9 - 10 gallons. Now I don't claim to be good at math but the tank is 12.6 gallons and IF I used 10 gallons, I should have at least 300 miles on the trip meter (30mpg worst case). I explained this to the service writer at the dealer and he talks down to me like I am stupid and Like I don't know anything about cars. I have also had problems with very rough idle when cold and the AC not getting cold enough. They claim they checked the AC and it was working the way it should. I have 2 other GM cars and have always bought GM and if that's the best the AC can do.... I might be moving away from GM in the future. My 2007 Sierra ext cab STILL makes the inside of the truck like an icebox after 8 years and ZERO AC service performed.

I also had issues with the transmission not actually shifting when I put it in gear a few times, the car would not move and the Drive indicator on the dash was flashing on and off at me. I have to turn the car off then back on to get the car moving again.
I am generally VERY disappointed in this car. I bought it because of the fuel economy and I can't get good MPG even on a long trip with ALL highway miles. The gas gauge tells me i am empty and the low fuel warning is on, but when I fill up, I only get 9 or 10 gallons pumped in before full again.
I do NOT like talking to the service writer at Jerry's as he is very rude and talks to you like you are stupid. I just had the car to the dealer a month ago and when I got it back the paperwork stated no problem found on the rough idle and mileage concerns, but when I asked him if they road tested the car, he said no. How can you find a problem if you don't even take the car for a ride????

I should have bought a cruze. Sonics have over inflated MPG numbers that you never hit if you leave it stock.

Also, I don't want to hear I need a "driver mod" I am very easy on the accelerator when getting into traffic.

 

[kevjam79]

Over 70 mph, the 1.8 drinks fuel. You can lose 2-3 mpg if you are consistently over 70. Keep in mind even with hypermiling the 1.8 Auto, you will only achieve a 35 mpg. I have a large set of data that I need to post but have not had the time. Maybe I will find some time today....

The cold start rough idle is a known issue by GM and the engineers at TAC. They are working on a solution. There is a TSB also. Based on my research and what I have found from watching my scan tool... On colder humid days, the engine is flooded with gas on start up and it begins to diesel. Please find another dealer that is willing to help and report this.

On the AC, you probably have a leak. My AC and my buddy's blows super cold.

On the Auto unresponsive nature, I honestly think that our transmission are installed/filled with air on accident or not purged. I noticed the same issues for ~1,000 miles... Then it went away. Sure the tranny is still learning but it was so sporadic... It seemed like air moving through the valve body.

Good luck.


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[shovey]

They claimed to have checked the refrigerant level and found no problem.

The only way to keep the car bearable is to keep recirculate turned on all the time. My other car and truck make ice on the outside air setting, I never turn recirc on with those vehicles.

 

[shovey]

I also think that maybe the fuel gauge is off by 2 gallons roughly

 

[shovey]

I pm'd the GM rep that posts here and he/she won't reply to me. Apparently that's how chevy rolls these days.

 

[Lazza]

You should definitely go to another dealer for service if at all possible. It sounds like your dealer is just wasting your time.

I live in south Florida and, like today, the weather can get up to the lower 90s with high humidity. I would say the a/c can just about keep up, although passengers in the rear might get a little sweaty. Can't you get one of those fancy "guns" and Home Depot, point it to a vent and see if the air being spewed out is sufficiently cool (under 70 degrees)? Such a gun shouldn't cost much, ... you can get them real cheap on Amazon.

Hang in there.


_Lazza

 

[kevjam79]

The GM rep doesn't work this site everyday. You should get a response by Monday.


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[SuperFudd]

Do try another dealership. Most dealerships want your service business, in and out of warrantee, no matter where you bought your car.
Have you used your car's computer to read average mpg? I commute 18 miles each way, Union City Ca. to Oakland. 90% freeway I-880. When moving well, 50 - 60 mph I get ~44 mpg . When not so well I can usually manage 40 mpg.
Note that I have a 1.8 automatic.
If I let the computer (DIC?) measure an entire tank I typically get 27 - 30 mpg.
That said, you do seem to have a problem on the drivability issue alone. I have never had a rough idle. I would suspect spark plug gap. These cars often have poorly gaped plugs from the factory. It could also explain your mpg.
I suggest the next time you bring your Sonic in, you do not mention your mpg or only "in passing" unless asked. It tends to turn service reps off. Focus on drivability issues. You DO have a transmission problem.
Perhaps a computer problem could cause both the transmission and engine issues?
By the way, I have noticed it takes my Sonic longer than I would expect to fully warm up and mpg is not optimal until it does. Perhaps in truly cold weather it never does.
As for the A/C, yeah it is on the weak side in an attempt to meet Big Government's mpg dictates. For me here in the San Francisco area it has always done well though.
The Cruze has the same engines an transmissions except for gearing. Probably also the same A/C.

 

[mitdr774]

You may think you are good at driving for better economy, but in reality you may not be driving the car correct to actually get good economy. One of the most important factors on the highway is speed. The EPA numbers have always been optimistic if you travel at the posted maximum speed limit on most highways. They have gotten more realistic, but are off still. How fast are you going?

AC and heat work most efficiently at the lowest speed settings. When I still worked in the dealer the standard used was a 20* change from ambient, 6" in on the left center vent, on speed 1 or 2.

The fuel gauge appears to have a 1-2 gallon "reserve" capacity built in. Really you should never drop below 1/4 tank since this reduces the amount of fuel available to keep the pump cool. Its not an error in the gauge, its a built in "idiot proofing" feature.

 

[c-lo]

I own one. 5MT. it's been a decent car so far. 33-35MPG.