Should I refinance my car?

I'm 20 years old and I just bought a 2015 Hyundai Sonata from a dealer. I financed it and put $1500 down and trade in value for my old truck was another $1000. On the contract it says I still owe about $23, xxx I just want to know if I can lower that full price by refinancing or does refinancing only help lower the monthly payements. I feel like I rushed to get the car and didn't do much research but I can handle the payments (about 700 with the car not plus insurance) but the full price is what I think they took advantage of me with. Also, if I trade the car in for another new car is that possible if I still owe, or does the difference of what the trade in value and what the original price of the Elantra add on to the new car I want? The dealership I went to is a Honda/Hyundai that work together so if I could trade my car in I would want the Honda Accord or Hyundai Sonata, so any help would be greatly appreciated

99 Honda Accord-Check engine light and getting smogged?

I have a 99 Honda Accord. My check engine light came on recently and my coworker hooked up the code reader (or whatever its called) and got code P0420 which is "catalyst system efficiency below threshold". I read that it could be an oxygen sensor OR catalytic converter. My coworker cleared the code and I purchased the sensor. He cleared the code Friday, and it hasn't come back on as of yet. I have to get my car smogged for the registration. My coworker said I should do it now while the light is off. He said if the check engine light was going to come back on, it would have come on very soon after it being cleared. Does anyone know if this is true? I don't want to take it and have it fail, and I have the sensor so I could have a coworker replace it before I get it smogged. I live in California, I think that our emission standards are Really high here. Should I attempt to get it smogged while the light is not on?

Why does my car shake and drive like its weighed down when the AC is on?

I've got a 2001 Honda Accord 4cyl. I got it a year ago at 196k miles and it now has 198k miles and it's been well maintained in the past and we've kept it pretty well maintained but the AC makes the car shake no matter what, and when it's driving with it on, it doesn't accelerate as fast. My dad said its just stealing horsepower but I don't think my car should shake like it does. I don't want to spend the money to get a mechanic to look at it just yet and either way my parents don't believe me so I came to the Internet for help.

Is it possible that my lug nuts for my 2000 honda accord tight?

I recently bought some new steel rims for my car and I tightened them myself when i drive them they seem fine but when the roads are a little bit uneven I can hear something friction like I think… Do you think they are too tight? Bcuz i didn't use a torque wrench