Sure you didn't run over a highlighter?

I can't think of anything factory in an HHR that would be bright yellow.

 

Are you sure a wiener dog didn't get under there JK

I had that same bright yellow under my LT (auto trans) once or twice, I chalked it up to something they are spreading on the roads to melt the snow/ice, but could never confirm what it was

 

Have you had the car in for any service or gas attendent top up any fluids in the couple of weeks ?

 

I noticed something similar a couple of times with mine, except it's green. What color is the AC refrigerant? My windshield washer is blue, the engine coolant is pink, so that's the only thing left that I can think of.

Yves

 

I noticed this under my car last winter the only thing that I could figure out is rabbit piss. They like it under the car in snow haven't seen it since. Sounds stupid but don't know what else it could have been.

 

Alien rabit pee

 

Did you smell it? Do you or your neighbors own a cat???(ouch!)

 

Methinks it could be oil leak detector dye added by your mechanic when he was looking for your leak.It's fluorescent yellow-green.Now you have to find out from where it's emanating because you still have a leak.
Alternately,it could be A/C refrigerant oil.

 

Two HHR owners

Owner #1 What's that?

Owner #2 Uuuug Hmmm Looks like Dog pee.

Owner #1 You Smell

Owner #2 Uuuug Hmm Smell... smells like Dog pee.

Owner #1 You Taste

Owner #2 Uggh!

Owner #1 You taste

Owner #2 Ok...Uuug Hmm Taste ...Hmm Taste like Dog Pee.

Ownerr#1 Good thing we not step in it!

 

I noticed those little yellow marks under mine, too. No one else parks in my spot and the snow/substance has no odor I can detect. I use a blue washer fluid and the coolant is still from the factory. Could it be from some coating on the car being sloughed off by the wet snow itself? Most aftermarket antifreeze is bright green.