Winter in MN is pretty hard on a bike, with the salt and sand and slush doing their damage. My summer bike has 85k miles on it and my winter bike has 16k miles. With one-fifth the mileage, the winter bike has gone through as many components as the summer bike. Both are Cannondales, and hence aluminum. There's been some corrosion on the winter bike's frame, but I just scrape that off and paint over it. The first set of rims lasted 12k miles, with the rear blowing out the sidewall when it got too thin. (Why the rear and not the front? The rear gets a lot more use than the front because of slippery conditions--frost, ice, sand, etc. I finally got some studded tires for last winter, but they don't help with the sand, so braking continues to rely heavily on the rear.) Yes, I could prolong component life with more maintenance, but I don't have the time or desire. And with the commuting, buying new stuff is still far cheaper than taking the car.

Hubs: The bike came with Shimano Alivio hubs that have great seals. I can go several thousand miles and the grease still looks fresh.

Rear derailleur: Many, many years ago I bought a Grunge Guard boot for the rear derailleur. It's been working wonderfully. I haven't seen it on the market for quite some time. I'd love one for the front derailleur.

Chain: It seems to only go 200-300 miles before needing cleaning. In an ice cream bucket, I'll slosh it through water up to a dozen times before the water starts looking clear, at which time I throw in some cleaner. In a tough winter, it'll last 1k miles. In a not so tough, maybe another 500. (Again, it's the time vs more maintenance issue.)