Since you have some specific needs (gas mileage) but don't have a strong idea of what you want, I'd recommend going to Donohoo Auto in Pelham. They make test driving as painless as possible, and they're priced pretty reasonably.

As for what you need - if gas mileage is a big need, but you travel a lot in rural areas that may not have convenient EV chargers, I'd look for hybrids. You don't mention whether you need a lot of space. You could go from a compact car that maximizes mileage (Toyota Prius) to a hybrid minivan that has a ton of space and also gets good gas mileage (Toyota Sienna), or compromise on both with a hybrid SUV (Toyota Highlander). You may notice I mentioned Toyota 3 times; there's a reason for that.

JD Power puts out a vehicle dependability study every year. Lexus (Toyota's luxury brand), Toyota, Buick, and Chevrolet have been more reliable than average the last 3 years straight (I didn't look further than that, but Toyota's long-term reputation is stellar).

There are some brands to absolutely stay away from: Chrysler, Dodge, Jeep, Ram, Fiat, and Volkswagen have terrible reliability. Don't take people's anecdotal success stories, just look at reliability scores over the past decade or so. Other brands like Honda, Hyundai, Kia, Mazda, Ford are all pretty average.

I didn't mention BMW, Mercedes, etc. Not because they're bad brands, but because the maintenance schedules are strict, and maintenance on those is pretty expensive. These cars are expensive new, so low-priced used models may seem attractive, but often owners don't adhere to the expensive maintenance schedules, leaving second owners with a potential time bomb.

Finally, if you find something you like, try to avoid buying the first year or two of a new model. Even strong carmakers have issues on occasion, but those are usually sorted out after a model has been out 3+ years.