I like the idea, it's cool But net time you should look at these points to make it better:
- When you are going to do a edit with another background you have to bargain on light source, as seen here, you have sun going down somwhere behind cars but light on them s going from somwhere in front This can be also done in your editor
- I don't know if you used smoke file to do this smoke or paint brush in editor but in second case try to play with them a little. Blur them, copy blured one over non-blured one, smudge them, use another angle, use mor of the brushes. If you want to take advice, i use Clouds brushes (for example: http://www.brushking.eu/97/cloud-brushes.html)
- If you are going to make screenshot put your LFS graphics settings to MAX, even if you computer will produce 5 FPS, you will have best quality output. And when you make screenshot in very high resolution and then downscale it to for example to 800x450 (450p, my favourite widescreen resolution) you will gain "anti-alias effect". If you use photoshop dont forget to use Bicubic Sharper resampling
If you want to get some Hi-Res pictures use images.google.com and after entering the searched phrase (f.e: "city skyline") then select Large images only on te left or choose wanted dimensions