Spoilers for the S5 Finale. Mild spoilers for the S6 Finale.
Mine
"I guess I'll take my car."
Once, when he was a boy, Sam hated the Impala.
The Impala was Dad. It was hard, dark, furious, indestructible, always carrying them around someplace Sam never wanted to go.
He hated how his entire world could fit in the trunk. How he could never have anything for himself that wouldn't fit on a duffle. He hated the leather seats that glued to his skin, how alone he felt on the backseat while his brother and father talked about things that he was always too young to understand. He hated walking back from school to see Dean and Dad hunched over the hood, trading tools. He hated the smile only Dean could get out of his Dad and only when they were hunched under that hood.
He hated hearing the roar of the engine from blocks away, letting him know his time was up wherever he was. Dad was back, the car was back, they were moving on.
He dreamed of opening the back door and getting out on the road while it was still moving, rolling on the asphalt. Wondered how long it would take for Dad or Dean to notice. He dreamed of a life with a roof made of bricks and cement instead of metal and leather.
And he got it. For the briefest of moments, he got it.
Never felt like home, though.
Years later when Dean showed up on his living room and convinced him to go look for Dad, Sam had to hold his breath as he opened the car's door. He let himself drop against the seat, breathed in the smell, all his instincts screaming: home, home, home. He always found it odd how homesick he felt in Stanford for someone who never had a home. But he did. He did.
And on the very same weekend he realized where his home really was, he lost everything else.
Dean grabbed him and saved him and carried him and drove him and Sam cried, head flushed against the upholstery, not even remembering how many of his tears had that leather been soaked in before.
His life was back on a duffel, his world was back in the car. But he didn't hate it anymore.
The Impala was Dean. It was fierce, irrational, unconditional love, always protecting and guarding no matter what Sam did, no matter where Sam went.
The car was his life and Dean was his life and Sam was a man, no longer resentful of things he never had, just so glad to have his precious few.
The car, mullet rock, leather, whisky, gun powder, Dean.
Then the Apocalypse came. And he had to watch through Lucifer's eyes to really see.
The Impala was Sam's. His life, his home, guardian of his tears and his blood and his family.
The Impala was Sam.
"- That's mine.
- Are you sure?
- Oh yeah."