I think it's kinda missing the main issue(a little bit)
If this is a tracing, or even just a reproduction of the reference photo, the overall issue is that the Engine is placed into an imagined background, or a background from a different reference photo. (I'm taking a leap and guessing this is the case)
What causes it to be 'jarring', is not necessarily the odd perspective of the Engine, but that the perspective of the Engine clashes with the perspective of the environment. The perspective of the engine (though to me it still reads as though the back of the canopy slopes down towards the back wheels) may be correct to the reference image, but because that odd perspective (or lens effect/focal length warping) doesn't continue into the surroundings, it looks out of place.
I just fiddled around with it a tiny bit, really only by changing the horizon.
I 'think' changing the horizon would help with the perspective issue, but it also puts you close to the ground, so the detail in the foreground grass and flowers would need to be adjusted.
Keep in mind, I (and I think the others) are just trying to be helpful, not trying to bring you down! So you are totally in control of telling us to go suck a lemon, if you disagree.