Plastic underbody panels on cars... What are they good for?

[Jedz123]

So my 2017 Honda Fit overall has been an exceptional vehicle offering reliability, fuel economy (AVG of 43MPG), versatility (2000lbs towing capacity) and driving fun (130Hp V-TEC engine parried with 6 speed manual and a car that weighs under 2600lbs).

However the thing is shedding it's underbody plastic parts. In the winter it has caused more issue as it tend to capture snow and snare me in tough spots.

Today (4'F) another panel has come free and wedged itself directly under the car (where I can't reach) and it's dragging horrifically loud and spraying salt and sand under my car...

What a PITA. With my past cars I never had plastic under body panels as layered as this one. I have permanently removed any panel that has caused issues. Over the summer I had an inner panel near the front tire come off causing loud banging and rubbing on the wheel. I cut it out so I could just drive down the road...

As I remove the panel I spray the parts exposed with underbody oil. I think today when I remove another panel I will just remove all that remain.

I got off the horn with my mechanic who is booked and can't remove the panel for me but strongly recommends I remove panels and oil coat as the panels are known to cause accelerated underbody rot by retaining brine and moisture more than no panel.

Bananas....

Anyway just doing some friendly venting on what I perceive as a design to promote underbody carriage rot and unneeded stops to the shop.

What are these under body panels good for? 2 extra MPGs?

[Baatfam]

I love them on my Fiat.
They keep the engine clean. It still looks like a new car under the hood, even though it is over four years old.
Never had one come loose or fall off, either. But to be fair, I don't drive in the snow.

[dpep]

What are these under body panels good for? 2 extra MPGs?

Fuel economy would be my guess.
...

[Cipher]

2 mpg over the service life is amazing and at least 5% on a 40 mpg car.
Also greatly helps the EPA numbers by offsetting a manufacturers thirstier vehicles.
EPA averages all production for a given year. Which makes gas guzzlers cheaper and that's where the profit lies.

[Jethro]

Hey, at least your oil pan isn't plastic like my f150!

[Jedz123]

So it's definitely a ploy to just sneak some mean/avg MPG of the fleet for the manufacturers than to drive sales for bigger (more profitable vehicles)?

My rubbing panel dropped my car down to 38MPG. My MPG always drops this time of year due to denser air requires more fuel to burn correctly. I commute in the morning at 5-6AM which is the coldest, not uncommon to see 0'F average on my drive into work this time of year. Average is 38-40 winter. The inverse in the summer it's always north of 40MPG, 43MPG is usually what I get per fill. Towing a MC with my trailer it's 28-30MPG. (Beats my last vehicle my truck at 12-18mpg)

I never saw a drop in MPG as panels start to fall out. ON the highway (when I do happen to get there) I saw +45MPG a few times. Generally in the rural driving I do it's 40-45MPG I have maybe 20% plastic left under the car.

[Baatfam]

So it's definitely a ploy to just sneak some mean/avg MPG of the fleet for the manufacturers than to drive sales for bigger (more profitable vehicles)?

Not a ploy, a feature....

I am serious that I love them. I do wish all my cars had them.

[Jedz123]

Hey, at least your oil pan isn't plastic like my f150!

The car does have a plastic valve cover but I think that's it. Very much a Honda in the build quality around the engine and transmission.
Your the only one on the forum that has seen the mini beast tow with both of us in it...
Your truck is bad a$$ though...

[Baatfam]

Used to be only expensive, fancy cars had them. Just trickling down to the cheap seats.

[Jedz123]

Not a ploy, a feature....

I am serious that I love them. I do wish all my cars had them.

I'm sure that love would change the moment you under your car in the middle of a snow storm prying what has turned that convenience into a shovel that marrons your tiny car onto the mound of snow it made and now resides on.

I had this talk with Fit owners and all south of the Mason Dixon are in you camp as well, so clean. North, it causes rot city and headaches unless your car is a garage queen.

[skip]

I'll bet you'll find your MPG drops this time of year because of the amount of time the car will sit warming up. While it's warming up you're actually building negative miles per gallon. If it sits for 5 minutes running at 1000rpm, it's got to drive for 5 minutes just to get back to zero mpg.

[Jedz123]

Used to be only expensive, fancy cars had them. Just trickling down to the cheap seats.

I remember in the mid 90's the Corvette had them for performance and wind resistance. My uncle's vette would get 30's MPG when we commuted from NC to NY in the summer together to visit family at home...
But when the cars just go through hell up here in New England these plastic bits just are a PITA.
To be fair my Yaris had plastic too... But it never was an issue. Maybe a quality issue that Honda let slip.

[Cipher]

I'm sure that love would change the moment you under your car in the middle of a snow storm prying what has turned that convenience into a shovel that marrons your tiny car onto the mound of snow it made and now resides on.

I had this talk with Fit owners and all south of the Mason Dixon are in you camp as well, so clean. North, it causes rot city and headaches unless your car is a garage queen.

Clearly some people shouldn't drive.

[Jedz123]

I'll bet you'll find your MPG drops this time of year because of the amount of time the car will sit warming up. While it's warming up you're actually building negative miles per gallon. If it sits for 5 minutes running at 1000rpm, it's got to drive for 5 minutes just to get back to zero mpg.

My car doesn't warm up unless driven, so I try to start driving ASAP.... It's an issue with these Direct Injected engines... I was late for work because the car never warmed up and the windshield was freezing over... A K24 swap should fix that. I have noticed all but overheating issues with my 1.5L.
Issues with the Earth Dream Engine

[Jedz123]

Clearly some people shouldn't drive.

Implying I shouldn't?
I can attest that I've driven in the north country for the past 23 years and can get myself out of a pickle just fine and drove FWD cars almost the whole time.
Buying new vehicles I have seen a dip in reliability and design issues that have definitely impeded the practicality of a Vermont car.
Clearly some people look to kick purely to do so.