Why is my car floor wet when it rains?

I recently bought a used Honda Civic, and it runs great around the neighborhood, but when I take it on the highway, the engine starts to misfire. Anything over 3000 RPM seems to be too much for the engine. What causes a misfire at high RPM? Can it be fixed easily?

I’m thinking about getting a Jeep for my next car, but I’ve heard they can be expensive. I’m handy with cars and can fix most things on my own, but if the parts are too expensive I don’t know if it will be worth it. Are Jeep parts expensive?

I’ve been picking my little sister up from her job at the mall and she always takes about 30 minutes to actually come out after her shift ends. I get so bored—there’s not much reception in the area so I’m left listening to the radio. What’s the easiest way to keep the radio on when the car is off?