While keeping a car you don't like could make more financial sense, you have to ask yourself if it's worth the emotional pain? You already don't like it, how's it going to feel when you have to put money into it (or just leaving it at the dealer) for services needed?
Cars depreciate. All of them. Yeah, some more than others, and at different times, but cars aren't an investment. And if you can afford to put a couple grand into getting into something you like, especially if its something your in every day, it might just be worth it for your overall well-being.
And as others have stated, don't just assume you are going to get screwed trading it in. Know what the car is going for (not just what one site says it's valued at). You can use that when haggling with a dealership. And the tax savings may be more noticeable than you would think.