Except for a few nights here and there, there are only 5 times that the Impala served as their home.
When Mary died, they had stayed with one of Mary's friends, Until the demon killed her, too, and left a message that he was after the boys. John gathered the sleeping children and their meager belongings, loaded them into the Impala, and away they went. They had nowhere to go. They had no one to help them. So, they just drove.
During the day the boys would play in the backseat. At night, the 3 of them huddled together with one of John's arms around each of his sons. He was determined to keep them safe.
Somehow, John ran across Pastor Jim and he provided them with their first shelter since they'd been on the road. John left the boys with Pastor Jim for a week or so. He needed to clear his head and find a way to kill the demon and yet take care of the boys. On this journey of his, John met Bobby, a fellow hunter.
It was summertime when they left Pastor Jim. John took the boys on a 'vacation'. They stayed in the Impala, but they were able to visit the Minnesota State Parks, swim in the lakes, and enjoy the sun. John kept the images of his boys splashing in the water filed in the back of his mind. They were able to be carefree, even if just for a short period.
John wanted his family back to how it was. He wanted Mary back. He knew that was impossible, so he tried to forge family ties with people like Pastor Jim to give the boys something to resemble a family.
When their vacation came to a close, they were welcomed with open arms at Bobby's. The boys had their own room with bunk beds that Bobby made, knowing they'd be spending time with him. Bobby knew no one could replace their mom, but he wanted to make a home for them nonetheless.
Sammy and Dean accepted Bobby as a protector and friend. He tried to teach Dean how to write his letters with Sammy crawling all over him, starving for Bobby's attention at just that moment.
John drifted in and out of the house. Sometimes he'd gone looking for something to hunt.
For the next few years, they seemed to alternate between staying with Pastor Jim and Bobby. Dean and Sam relied on each other. Pastor Jim and Bobby didn't mind the boys because they'd grown to love them like their own.
Then, John and Bobby had a big blowout. The boys never knew what caused it. John never spoke about it. Their Bobby, and all he had been to them, was gone.
It was back to being on the road. The Impala was home and her family was outgrowing her. They drove most of the day. At night, John gave the boys the backseat so they could lie down. He snoozed in the front seat.
John kept making contacts with other hunters. He'd go visit them after the boys were asleep. He never introduced Dean and Sam to anyone until he was as sure as he could ever be that they were okay and safe.
Caleb's was another place that their Impala stopped. Caleb didn't have much but he shared what he had. Dean liked Caleb but for some reason, Sam just never took to him. Their stay with Caleb was cut short when Pastor Jim phoned to ask John for his help. Soon, they were on the road again to another of their homes.
Somehow, John made up with Bobby and they were able to stay there again. John would try to stay long enough for the boys to go to school. Sometimes he did. Sometimes he didn't.
Years later when Sam was at college, Dean stayed in the Impala when he went on hunts. He didn't want to spend any of his hard-earned money on a room he wouldn't hardly be in. Living in the Impala made him feel more mobile. With John and Dean working different jobs, he felt free. It was just him and his baby.
After Dean got Sam from college and Jess died, they stayed in the Impala. Sam didn't want to bother any of his friends for a place to stay. He didn't want to be able to be found. So, he and Dean looked for signs of the demon during the day and slept sitting upright in the backseat at night. Sam had his nightmares and Dean had to be nearby to wake Sam up. After Jess's funeral, they left California. That's also the last time the Impala was used as a home. Sam and Dean had grown apart during Sam's time at college and they needed the extra space to get used to each other again.
The two of them deserved a roof over their head at night, that included running water. They didn't stay in anything fancy, but it was more than the Impala could provide for them at their age.