I have been viewing this thread for years and enjoy the great content. I do not post much, however, I had a MVI completed on my 2009 Honda Fit (Canada) and received some shocking news, the frame from rear bumper to spring has completed corroded away! At first glance this car is in great shape. No rust on the body or under the hood. Even very little on the rear wheel wells. Has anyone else on the forum have any issues with frame corrosion? I live in Newfoundland and we do use a lot of. salt on the roads but I have owned Hondas from the late 1990s and early 2000s that are still on the road and in good shape.

 

My level of "shock" would depend on how the car was cared for during your ownership (and prior to you if you're not the original owner).
If you told me that the car was rarely or never cleaned (including underbody) over its 10+ winters then I would not be surprised by the level of rust you're seeing. I've seen far worse on newer vehicles in high-salt areas.
If you told me that the car was rarely driven in the winter, or the underbody was sprayed off regularly during the winter, then I would be mildly surprised, but again, you're dealing with 10+ winters in what you describe as a high salt area.
If you told me that the car was fine at your last inspection and is now in the condition shown in the picture, I would be very confused.

When you say you've had older Hondas last longer, did you own them for the same amount of time/distance driven? Were they driven on the same roads and same salt conditions? Did you care for them differently than the Fit? Again, in my experience older vehicles were more likely to rust than newer vehicles under the same conditions. Having said that, it is always possible that some error was made in the production of your vehicle that made it especially prone to rust, but if that was the case I would expect your entire underbody to be a rusty mess and not just the rear of the car.

Were your other Honda vehicles hatchbacks? This is just an idea, but I know from my previous Yaris hatchback and my current Fit that the body style and associated aerodynamics create a pretty massive eddy behind the vehicle (e.g., I had to use the Yaris rear wiper constantly in the winter because the window was always covered with road gunk; my 2010 Fit Sport isn't quite as bad, so maybe the spoiler helps a bit). Maybe hatchback aerodynamics lead to more salt and debris being trapped/collected under the rear area of the car than on a similar sedan?

 

I've had my '09 since it was new and it's been exposed to northern Ohio winters. We get a lot of salt too, but our salt season is probably shorter than Newfoundland. Most GE Fits that I've seen around here don't have any visible rust, but I did see one a couple of years ago that was astonishingly rusty - wheel wells, door bottom edges, etc. So they do rust under the right conditions and level of care. Mine is practically rust free, but I'm very diligent with rinsing off the salt whenever the temperature gets above freezing. I use a lawn sprinkler attached to the end of a 2x4 and sweep it back and forth under the car. Most people wouldn't think this is fun, and even with rubber gloves it is a pain in the neck and my fingers get very cold. But the reward is that my '09 Fit looks like this (the red things are Air Lift 1000 air helper springs).

 

@Ultrawolf That's one heck of a contrast! I'm really appreciative also to see how well your chassis has faired with maintenance.

@jwarren2009 How many winters has your fit seen?Another consideration for corrosion may be the brine used for roads in your area. I'm not sure how one would look into this, but if others in your area are seeing such extensive corrosion there may be a direction for you to head in.

I'm terribly sorry to see what's happened to your car

 

Can't say i'm surprised for Canada, let alone Newfoundland. Not sure if the air is salty throughout the island, but I'm sure by the coast it is.

For reference, here's a photo of my Fit's rear end at August '20 when it had 546k miles (880k kilometers). Currently has 576k miles (928k km). The car has rarely been cleaned up while living most of its life in New Jersey from 2008-2016 at 390k miles (627k km)



This is applied to any car, despite the body style. Ever noticed when a car drives through powdery snow or a gravel road that the rear end is always covered? The same goes for the underside. Here's a photo of my daily before the Fit: a '98 Jetta TDI. The end of the exhaust was pointed down, but the soot always ended up at the back.