What is the best economical thing to do in this situation?

I bought a 2008 used Toyota Camry Hybrid.

It had a hundred and thirty thousand miles on it so I got the extended warranty.

I'm thinking when the warranty runs out I'm definitely going to sell it or trade it.

There are a lot of gasoline engines that get comparable gas mileage to the 2008 Toyota Camry Hybrid so now I'm looking at them.

I'm now looking at a 2013 Ford Fusion.

The dealer offered me a substantial amount for my car.

Based on what I have invested into the car, not including taxes, it cost me about 230 a month to drive.

Since I Drive a lot, I have a feeling I will get a lot last after two years when I plan to sell it.

I think if I get out now, I can save myself a lot of money in the long run even though I lost out on a little bit.

Diffusion has only 50,000 miles on it which is less than half of mine now.

The hybrid car is great, but I don't feel like playing Russian roulette with the hybrid battery pack which could go bad at any time a $5,000 expense

First of all, the hybrid battery is nowhere close to a 5,000 expense. It's just over $2,000 now.
Those batteries last well over 200K miles and 10 years. I wouldn't worry about it. As long as it's not costing you a lot to maintain it, then it would be financially dumb to get rid of it.

When it comes to diffusion, it's way above my pay grade. I'd speak to an engineer, maybe the diffusion could be remedied in some other manner.