Concept car render with cycles

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The reason why I'm learning computer graphics and have computer is because I like to design my own cars.Here is my best so far concept car called vikintador.Shape was created on aventadors wheel basis.I want it to give more aggressive and powerful look to this supercar,just the way I like it.It was designed 2 months ago,and before cycles render I used yafaray realistic rendering plugin.Model was created with blender3d and rendered with cycles new internal render for blender3d 2.60.For the light sources I'v been using 4 lights from every side of the vehicle and one plane from the top.For the background image I used hdr image.For the final image I used 200 samples.What I didn't get it,is how to create transparent glass(light group) without noise and with reflections.If you have any advices how to improve my rendering,please let me know.Enjoy my concept.;)Attachment 85600 Attachment 85601