There is so much really good art created by artists in the SPN fandom. I've seen quite a few comments on how difficult cars are to draw but there are a lot of successes out there. Here is the tip of the iceberg with some Impala art recs in many different kinds of media. A lot of these have the Impala in a different form than the car we often see. It's all SFW. Feel free to rec others in the comments.
Carry On My Wayward Son by Alice X. Zhang
Team Free Will with the car.
Casefic art masterpost for The Best Things in Life Are Free by amberdreams
A great art rendering of the use of the rearview mirror to catch a view of what Dean sees behind him.
Impala Shopping Cart by KristalStittle
The Impala as a shopping cart.
"Baby" Chevrolet impala 67 - Supernatural by Carella-art
Water color painting.
Dark Side of the Impala by alrtist
The Impala as a Pink Floyd album.
The Good Old Days and Sleep Well America by petite-madame
One ink and watercolor pen showing the open hood of the car and one digital painting of the car, post-hunt.
Just Off the I-95 by maichan-art
I like the subdued color and the isolated feeling I get from this fanfic illustration. This one has stayed with me.
Supernatural Impala by allthingslauralike
Digital drawing of Impala and tattoo.
TFA Impala by HaloSon
The Impala as a Transformer.
And another take on that idea
TFA - Impala Sheet by Lizkay
ChA - Dean's '67 Impala by ChrisArrizabalaga
Charcoal and white coal pencil.
Impardis by SirGeorgPrime
Doctor Who take on the Impala for everyone like my kid excited for the new season.
In the Light by Five--Oclock
The Impala with a cool Milky Way backdrop.
Space Impala by Kickbeat
The Impala as a spaceship.
Plush Metallicar by ldhenson
What it says on the tin.
Dean and Impala by slugette
The Impalas by Rogoon007
The Impala as a drummer in a rock band.