As a counterpoint to nocturnal_tick’s thread about driving and encountering a thoroughly unpleasant odor, I thought I’d share an experience I used to have every day.
On my way to work I used to drive past a biscuit factory. The entire suburb used to smell like freshly baked choc-chip bickies.
For that matter I love the smell of a two-stroke motorcycles exhaust and the waft of exhaust from a jet turbine.
Anyone like to share a good smell while driving or a smell you love that you shouldn’t?
Merita bread, I believe, has a plant right by I-4. There are good smells coming from there often, but especially around 3-5 am…mmmmm, yeast+bread.
I drive by a small lumber mill almost every day, the smell of the fresh cut wood is awesome. we also drive past a composting plant that absolutely stinks! 
Mmmm, fresh baked bread smells.
In Cincinnati between exits 6-9 on I-75 one often gets whiffs of the different flavor liquers being created by the DeKuypers plant there. I liked most of them. Sadly the Ivory Soap factory is also in the vicinity, so certain odors from there were most unpleasant and would often win out over the scent of good, particularly on hot summer days.
Near my house is a Kellogg’s factory, and most afternoons when my sister drove my brother and I home from school, there was the most delicious scent of Pop-Tarts. Mmm… pop-tarts…
Wow that’s weird! Ludovic I came in here to type JUST WHAT YOU DID!! I was born and raised in Orlando but have live in Altamonte Springs for about 10 years now. The Merita Bread factor was “half-way home” from a friend’s house to mine many years ago! 
MMMMMMMMMmmmmmm…fresh baked bread!
I used to drive down I-87 in “Da Bronx” right past the Stella D’oro plant-never failed to make me hungry!
If you time it right, when you drive down the 210 Freeway in Irwindale, you can catch the aroma of malt and hops from the Miller Brewery.
Lovely smell. Crap beer, but a lovely smell.
One of the fuel-blenders in the state got a shipment of off-spec perfume. Tankers and tankers. So this plant went from smelling like used motor oil and fingernail polish remover to smelling like a spring meadow. It was lovely. Too bad it didn’t last.
My husband talks about driving down an road near Lompoc, CA and following a open bed truck carrying freshly-pressed lemons from a juice factory to another plant. He wouldn’t pass the truck because all that lemon oil and juice was leaking and making the whole world lemony fresh.
I drive past a Wonder Bread bakery on the way to work. It’s amazing that such crappy bread can smell so good - almost as good as real bread.
My grandmother used to live about four blocks from the Life Saver factory in Hamilton, Ontario. The whole area smelled heavenly, particularly on the days when they were making Butter Rum or Wint-O-Green flavors.
My town hosts both an onion dehydrator and a couple of tomato packing plants. When the wind is right, it smells like marinara. Mmmmm!
Where I used to live I drove past a Jif plant. Right about the time I got off work every night the plant was roasting peanuts. Wow, what a great smell.
When I was riding my bicycle to work, I often had to struggle to keep my eyes open when thirty feet of honeysuckle vines on a fence engulfed me in their scent. Oh, boy, oh, boy!
A friend of mine is from North Judson, Indiana, in Starke County. They claim to be the mint capital of the world. In the fall, the farmers cut the mint plants and load them into big wire-cage wagons for transport to the presses. The wagons have boilers to steam the mint on the way. After pressing, the mint is returned to the fields for compost. Dave says the aroma during harvest will nearly knock you off your motorcycle. Some North Judsonites say Altoids are for wimps.
Wow, guys, I’m jealous! I don’t have any nifty-smelling places to drive past… But here’s a strange scent I love: Elevator Grease. Currently, I know of only two elevators that have this odor- work, and the Post Office. I make a point to ride alone so I can fully savor the aroma without anyone thinking I’m kooky.
The Folger’s coffee roastery in downtown KC.
Need I say more?
Up until a few years ago, we had an Italian bread bakery in my neighborhood. They produced thousands of loaves and rolls each night, to supply many restaurants, mom and pop stores, deli’s, etc. There’s something very basic about the warm, yeasty aroma to which most people can respond positively. They’d sell you bread hot out of the oven. Not so great on a steamy August night, but in mid-winter it was a real treat.
It closed a while back, but growing up the Mrs. Bairds bakery was in town. The fresh bread smell would make you hungry as you drove by.
I used to walk with my mom when I was younger and there was honeysuckle gorwing somewhere in a field near the road, so in one certain spot, the scent was strong and wonderful.
The Taekwondo school I used to attend was downwind from a Chinese restaraunt. Whenever I left after a good workout and the wind was right, I’d get a snootful of soy, garlic, and ginger aromas. Always made me hungry.
Much more recently, I was walking to the cafeteria on Pasta Bar day, and I could smell the garlic a quarter mile away. That time it annoyed me, because I’m doing Atkins, and couldn’t have any.
Necco Wafers! Sky Bars! When I first lived in Cambridge, Mass., the Necco factory outside Central Square used to send blasts of chocolate-flavored air through the Riverside neighborhood…how utterly lovely on a warm spring day…mmmm.