And sometimes the same colour as the bumper (when the bumper is not the same colour as the car itself) and is usally at around half way between the top and bottom of the doors?
Side trim
Door trim
Auto trim
Many names for one product.
That would be a molding. A rose by any other name…
Oops! In your case, a moulding.
Body side molding, and if it’s really broad, cladding.
Beltline molding.
My friends who worked in the car industry called it “cladding.”
As in: “the cladding on the Aztec looks really cheap.” 
I called it “horrid” when it applied to the foot wide trim on the late 80’s Pontiacs.
Also applies to Chevy Avalanche (half cladding, half truck.)
In the UK it would be called a valence.
Stupid valences! :smack: That’s why I got a D in Chemistry. 
:smack:
I had one of those. I called it a dirt collector. Stupid grooves were a pain in the neck to clean. I did like that it gave me some protection against over zealous neighboring door openers in parking lots.
Anything that attaches to the side of the car, other than paint / tape stripes is usually called a molding. If it is about half way up the door, it is sometimes called a belt line molding, or a rub strip.
Trim, molding, cladding, stripe, rub strip… Can’t you Anglos agree on a term ?