One of the things that I like about bicycling that I think you miss in a car is the scents that surround you.
Too often it's stinky car exhaust, but sometimes it's like a secret window into the workings of the city around you.
Around MIT I often get to smell the candy factory. Cambridge MA used to be "the Candy Capitol of the Country" with Squirrel Nut Brands, Necco, DeHaviland and other candy brands which are or are on their way to being defunct. One remnant is the factory between Main and Mass Ave. The building sign says Tootsie Rolls, but it often smells like peppermint patties to me.
At the corner of Trowbridge and Broadway there's a little pizza place with a house above it. I don't know if it's pizza prep or breakfast but it always smells like bacon when I bike by in the morning.
This evening on the way to the grocery store, I could smell the coffee roastery at Whole Foods from probably 6 blocks away. Coffee roasting is such an odd smell, only distantly related to the comforting smell of a pot brewing.
I have two very different memories associated with that smell. One is the seedy part of town down near the Port of Houston where I used to go for industrial scrap dumpster diving, good mexican food, and photography projects. The port of Houston, if you aren't familiar with it, is 70 miles inland. When Galveston got completely flattened in the Hurricane of 1900, the City Fathers of Houston decided that if they could create a hurricane proof port inland, it would be great for business. It was a massive undertaking to dredge such a deep channel so far, and it's really odd to see these HUGE ships so far inland. Anyway, there is or used to be a Hills Bros coffee roastery there and the whole area reeks of it.
The other memory associated with this is when I lived in Italy and the high class coffee places would advertise "torrefazione nel propria" roasted in our own.
More often the smells are commonplace- dinner being made, fresh mown lawn, sometimes something less savory. Not only are there no windows between you and the smells, but you move through space more slowly so that you can appreciate (or suffer) them longer and more immediately.