You mentioned the Prius, so allow me to evangelize a moment. If your price threshold is $20K, the Prius is probably not be the car for you, but I have almost nothing but positive things to say about the two that I’ve owned. It is a decently comfortable vehicle, and it has more room than you might expect. With the back seat folded down, there is a good amount of cargo room. It is not a rocket ship, but I have never been concerned about merging onto the highway safely or doing any maneuvers I might want to do in my generally conservative driving style.
The mileage will depend a great deal on the kind of driving you do and the way you drive. The first Prius I owned was driven about 90 miles a day, mostly on the interstate and county highways. Over 30,000 miles (before I was in a wreck and totalled it), I averaged just over 50 mpg (I kept track of every tank of gas; this is the actual number). After that wreck, I replaced that Prius with another one. I also switched jobs, so my wife now drives the Prius since she drives more miles. I have not figured the overall mileage recently, but I’d estimate the current mileage is somewhere around 45-48 mpg. The difference is probaby due to my wife’s commute, which involves more idling in traffic, and her driving style, which is more aggressive.
I do have a few complaints about the car. The visibility out the back is not great, and the beeping warning that starts when I put the car in reverse is freakin’ annoying. But overall, I like the car quite a lot.
I don’t have any quantitative data on safety, but when I wrecked the first car in a near-head-on at 65 mph, I walked away with just a dislocated rib. From a pure operating cost standpoint, you might be better off with a small, high-mileage car (maybe a Yaris or something), but as I mentioned above, the Prius is a larger car, which might be attractive to you if you’re hauling stuff. Also, I drive ours the 400 miles from Cincy to St. Louis every 6 weeks or so, and it’s pretty comfortable for that.
Anyway, if your pocketbook will accept it, I encourage you to take a look at the Prius. If I were buying a car today, I’d look very seriously at one, but I’d also look at the smaller high-mileage cars that are out there now. I haven’t looked at new cars for a couple of years, so I don’t know what else is available.
Best of luck in your search. I hope you find something that fits your needs and budget.