I'm buying a used car and I hope I don't fall apart

In about 2008, I started driving a 2002 Nissan Maxima.  My brother found a really good deal, and my parents bought it.  They had it for a little while and then gave it to me, which I still appreciate.  I've now had this car for 10 years.  It has nearly 300,000 miles and the registration is up at the end of august.  I can't get it to pass emissions and there's a code for a major problem with the transmission. Over the years, I've never had any major problems with it. I've kept up with the maintenance.  Early on in the car's life, my brother would take care of it for me.  He changed the brake pads a number of times.  He would take it and wash it for me.  We took it on a couple of road trips. In fact, the time that sealed for me that there was something wrong with Josh, he was trying to change the brake pads for me and couldn't get the old ones off.  This was never an issue in the past.  I had a pretty serious conversation with him when he told me he was just worn out and couldn't get the pads off.  Joshua loved this car.  After all this time, and after all of these miles, the only thing I love about this car is the memories it holds of my brother.  As the time marches on and he's been gone for nearly two years, the physical things that tie he and I together, are beginning to go away.  I can't keep this car.  It started vibrating so bad today, I didn't drive it on the freeway.  I took the back roads to work.  Much like every other story I've told you about my brother, there's a number of things that make smile, and number of things that make me cry.  If you go back and read the eulogy I delivered for my brother, you'll recall that my brother loved cars, and particularly loved Nissans.  I didn't think about it much until yesterday when Christa, the babies, and I stopped by the Nissan dealership and I test drove a couple of Sentra's.  Joshua's first big boy car was a Sentra.  I have decided that I'm going to buy a Sentra.  I don't know if it seems silly to you, but I miss him.  I miss him every day.  The days are easier to deal with now, but every once in a while, a flood comes. Josh would be happy that I'm getting another Nissan.  He would probably take it out and wash it for me.  He would tell me to get different wheels because this one has hubcaps, I would tell him that it's a good idea, do you want to pay for it?  He would tell me no and secretly look for good deals for Nissan Sentra wheels, and I would probably buy them, but he would put them on for me, because also loved wheels and tires so much.  He would ask me if he could borrow it, and I would tell him no, and he would get mad, but then I would relent.  He would probably end up buying it from me in a couple years because he would've found a great deal on another car for me.  There isn't a doubt in my mind that all of these things would happen.  Unfortunately.  They won't.  If you're reading this, and you know that you're sicker than you're letting anyone know about, go to the doctor.  If you feel like you can't tell anyone because of embarrassment, I will take you to the doctor in the car that I'm buying tomorrow night.