Has anyone ever used a tinted undercoating to somewhat match the body color? Many have painted the underside body color and that was my original intent but I’d like a little more durability so I’m not worrying about stone chips every time I drive the thing! If you’ve done this, how good was the match and what brand of product did you use?

i am a PPG certified autobody tech / painter.
ALL car manufacturers dip their cars in a vat of epoxy prime these days. this is referred to as Ecoat. they paint the exposed panels with color and over spray gets in some areas on the bottom of the car. the areas not covered get left as is and driven. some arears get rusproofing sprayed in some areas to further protect them.
this is how the old mopars were painted back in the day.

all major paint manufacturers make tintable sealers. you could look into that.
they also make tintable bedliner.
https://www.amazon.com/Raptor-Tintable-Urethane-Spray-Liters/dp/B01CKE7M7M/

SEM makes spray bombs that are close matchers to factory Ecoat primers. i use this all of the time when working on inner panels of cars for corrosion protection.
https://www.semproducts.com/product/ez-coattm

in my OPINION. if you are looking for maximum durability. i would get a sample of the Ecoat you want to match. take it to a paint store and get a eye match mix of urethane single stage enamel paint made.
$$$ but it's durable. you could cut costs and use regular enamel paint. a LOT of people just spray the exterior color on the bottom and leave it that way.

there are large amount of under hood color mixes listed in paint code year color catalogs also. you could check these color for a match also.

i myself make a mix of epoxy primer that's close to original color and spray away and call it a day. the old cars rusted vbecause they were driven almosy every day and usually not taken care of. a restored car won't have this problem.

Thanks for the reply but I'm specifically interested in info about tintable undercoating/bedliner - and just how well it can be matched to the body color.

In this area - Inland Pacific Northwest - I've seen several pickups with tinted bedliner.
Seems to be a fairly limited range of colors, though I've seen some that matched the truck color.
Whether that's dumb luck or actually tintable, you'd best ask the various manufacturers or jobbers.
Some seem to fade, as though there's an issue with UV resistance.
We did spray-on bedliner as a side business at a dealership body shop, but only did black.
The surface was roughed with a coarse wire wheel, and heated liner applied with a high-pressure gun.

You will have to see what the manufacturer specifies. For example, when my buddy was selling Speedliner they reccomended PPG paint matched to the vehicle. I forget how much per gallon you mixed in but it didn't take much. I tried other paint on some side projects of my own and the color didn't keep for long.
Since you are wanting to coat the underside, UV fade will be minimized.

Stanton - I used the Raptor bed liner on the underside of my Runner.
I only used it in the front and rear wheel wells, the underside is finished painted.

It is tintable - I had the body shop supply place where I bought the kit make up a pint of the W1 Alpine white which I added to the Raptor.
I didn't use the supplied Schutz gun that came with the kit, instead I used a small 3' wide foam roller (less messy).
You can see by the photos the color was spot on.

I have tinted bedliner on the inside of my quarter panels.

that looks really good !
a question i have been wanting to ask about bed liner.
what kind of [minimal ?] prep is required ?
are the spray bombs [rustoelum] any good ? [i know this brand only comes in black, but that will work for me] and if so, just how tough does it set up ?
TIA as always.

I've used the spray bomb stuff and it has virtually no texture to it - more like a thick satin black paint than a textured bed liner. It does set up solid - not tacky.or soft. You won't get the above texture out of a spray bomb.

I also used it up behind the bumper.

Like to see how things look when the car is painted.

Here you go

And the color match is good? Whose product is that?

Color match is good. Especially for where I used it. It's the tintable Raptor.

You have gotten some good advice here. A couple things to remember though: If a jobber is mixing you some paint to add to raptor liner, it should be mixed without binder and balancer. You want the toners only.

Also, raptor is a great product but can become brittle over time. I have seen it crack before. Not that our cars are going to be subjected to the same kind of abuse that a truck bed would be under, but it helps to have all the information that you can get these days.

That looks really good. Question - did you spray the Raptor liner over the plastic body plugs? If not, were the plugs able to go back in the holes after the coating was applied?

I didn't spray it, but it didn't go on over the plugs and the plugs went back in fine.

I stopped in the shop one day and found my paint guy in the trunk sanding the trunk floor. I told him I really wasn't worried about the trunk floor and suggested that he just bedliner it. He suggested tinting it on the inside of the quarters.

My trunk floor's an ugly mess - not rotted but plenty of dings. My reason for wanting to spray it. I was also contemplating doing the whole underside in tinted stuff but I think I'm going to pass on that. Can always be done later.

I just with 80 grit or cup brush on a grinder. Cover any bare metal self etching primer. It takes ALOT of material to build any kind of thickness. Texturing is a learned thing. You can experiment to see what you like.

thank you.
the reason i ask is, i want to cover the exposed interior tin on my humpback with a gray [industrial type color] tinted bedliner.
the seats i will be using are the second row leather bucket seats that were in my 95 caravan. [bus]
they are "distressed", [but not ripped] and fit the theme of this build, plus fit my fabbed floor pan and transmission tunnel well, even before i get the mounts made.
i intend to have minimal gray colored leather on the door posts as well as matching the color on the roll cage padding where needed.
also a minimal cover above the windshield and door openings, as well as a few areas in the box.
the rest of the interior will be gray beadliner.
the doors will have bare aluminum door panels.
i was thinking around using a 60 grit, but i'm glad a wire wheel will work as well. thanks again for your response and suggestions.