has anyone noticed an issue with the economy on there turbo models? I have a 2013 LTZ 1.4 turbo and my average MPG is about 27 and since its colder with it idling more for warm up has dropped it to about 24/25 average MPG. Also, when its cold out and I start it and let idle shortly after it begins to run rough for a few seconds. Or, if I start when its cold and take off right away when I hit a stop sign and stop completely , the car wants to jerk forward about 5 times. I've complain to Chevy directly. Took to the dealer to be checked regarding MPG and they say nothing is wrong. Seems to me like they are trying to avoid an issue. My value has dropped substantially and I'm pissed. 24,000 miles.