Photographers: What should my NEXT camera lens be?

Hello fellow photographers and artists of image. I have a question. I consider myself an amateur photographer, but not a novice. I have a D3200 with two lenses. I have the 18-55mm VR Kit lens, as well as my stunning, affordable 50mm f1.8 Nikkor lens. Since I purchased my 50mill prime lens, I have touched my 18-55 very few times. I love the sharpness and speed that my 50mm delivers. I find my 18-55 to be practically useless for my photography needs unless far subjects are in the question.
My main subject of photography are cars. I also enjoy shooting close-up nature subject such as unique plants and animals. Fish, spiders, etc.
But mainly, i would classify myself as a car photographer.
My question to you wise folks is, what should my next lens be in my arsenal?
I understand the 50mm restricts myself to many things such as fixed focal length which can make it more difficult to compose the shot. I rarely stop down to 1.8. Usually between 2.2-3.5 does well on much of my car photos.
My price range is as affordable as i can be. I'd like to see some sharpness like I do with my 50mm but i understand some sharpness sacrificed with zoom lenses vs prime lenses.
Also one more side note: I'd like to produce photos such as the one attached. I believe a telephoto lens gives this nice depth of field and shot for a car photographer.
AGAIN, im still learning so bare with me. Thanks

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