Like Minux said, Av and Tv modes just calculate settings required based on one fixed and multiple unfixed variables. It won't change the effects any more than if you had chosen those same settings in full manual.
That being said, it can be very useful in certain situations. For example, I was shooting at a hilllclimb recently. At the top of the loops, the lighting chagned from dense tree cover, to full sunlight. Even with custom function switches set for sunlight and for shade, having to turn the dial from one to the other meant I missed a lot of shots in the middle. Too dark or too light, respectively. Choosing shutterspeed priority allowed it to change settings on the fly between shots, even at 8fps and changing from full sun to full shade, it was fast enough to get focus and still manage at least 6fps.
As for your photo, I'm not sold on the photoshop blur. Ech to their own, but it's too sudden. If the 50mm you're waiting on is a nifty fifty or something along those lines, with a fast maximum aperture, you would be able to isolate the front bar back to maybe half way back in the engine bay, minux? I can't think off the top of my head what DOF you might get from a 50mm @ f1.8 from... 3-5m? away. It would soften the sudden change from sharp to blurred, and get rid of the obvious edges like you see on the tyres.
