I have same vehicle, now with over 50K. Only serious engine problem has been a computer related stall-out. It was handled immediately by the dealer. Starts quickly everytime, hot or cold though. You'd probably be well advised to contact GM directly.
My Optra 1.8LT mileage is now 53000+/-km.
Check Engine light illuminates and hold light illuminates.
Send for repair : Check wiring harness and clean up the necessary connector.
Now, it has no problem at all. According to the appointed Chevrolet workshop, hot climate and dust is one of the reason why sometimes the connector failed to communicate with the engine management system.
I have a Suzuki Forenza (as it is called in the US). +-30K km... so far no problems although I have seen the complaint about not starting on a few sites.
Bought my 2006 Optra 5 automatic in September of 2005. Loved the look and Khaki color, the interior was great, but had problems right off the track!
From the beginning it lagged in shifting from second gear to drive, and since has been in the dealer shop two times for the problem. They replaced the shift module and had the same problems within the week. It's in the shop for the past week now with no word of the problem being corrected.
And the gas mileage... wow! Gas guzzler!!! If I knew it wasn't made in North America by Chevrolet, I wouldn't have bought it!
The resale value was a shock. I considered trading it in after the problems started, but didn't expect it to depreciate so much! 21 thousand to 9 thousand in 2 years, what a drop!!! Should have bought a Mazda 3!
To the first comment about not starting. Mine is a standard and I have the same problem on and off with it starting. GM (local & GM contact # from site) have both been telling me for 3 years that I am the only one to report this problem, and that they can't fix it because it does not happen every time. I have found it is not related to how hot/cold, wet/dry it is, for it to do this.