I own a Suzuki Swift A/T, and its mileage within city has never gone beyond 12.77 Km/l. It stays above 12 Km/l only if you drive with a light foot on the accelerator, otherwise expect 11 Km/l. I always drive it with A/C turned on. I didn't observe it during the winters period, so can't say if the mileage improves without A/C.
Never had any problems with the automatic transmission. Plus, I see people telling here that it is slow but it is not. To experience the full power, press the pedal fully and you'll notice the RPM meter will touch 7000 for the first 3 automatic gear shifts. For the 4th shift it goes to a maximum of 5500 RPM but not beyond that. Also, there is a protection in the car for the high RPMs. As soon as it detects that engine needs power (i.e. when pressing the accelerator in full to achieve high RPM), it will turn the A/C off automatically to avoid damage to engine.
Moreover, the tire pressure is also important when trying to get the maximum output from the car. As per the car instructions, the front wheels have to have a pressure of 33 psi. And the rear wheels have to have 30 psi if there are no persons and luggage on the rear, otherwise 37 psi is needed if there are people and luggage in the rear.
And I'm pretty sure most of the people are keeping it under 30 psi in all 4 tires and then complaining about the output. Not fair.
My only complaint with this car is that the cabin is not as silent on bumpy roads as it is in other cars.
On the other hand I do not care about the re-sale value. What is important is that you enjoy driving it and that I really do.