Bring it to Cambodia
and things will be drastically different. My neighbor has a V6 (Ecoboost) F-150 here and it does 9 mpg according to him, haha. In comparison, I have a Ford Ranger 2.5 delivery truck as well and it barely tops 14 in the city and it's a manual. I also run a Daewoo Damas van (1.0 L) for small deliveries and it too only does 30 mpg (manual). Again it's down to the horrible congestion here.
As for a different car, well, I just got this, and frankly there is nothing else over here that can be had that does any better, except a motorcycle or a Kubota diesel pickup. At least it seems that way.
I just bought some synthetic oil ($16.50 a quart....
) a new oil filter, and trans fluid, so we'll see how it improves, if at all afterwards.