gasoline. I loved every time we went to the gas station to fill up on gas. It was one of the best smells in the world.
That lasted all the way up until I was 16 or 17. Me and my dad replaced the gas tank in an old VW bug. I hate the smell of gas now. I abhor it.
Side note, it was years later that my dad realized how dumb of a move that we'd made when we replaced it. We did it in our garage where the water heater was. Water heater had a pilot light of course. All those fumes in an enclosed space? We were lucky.