Cyrus, the Silvia looks great. Go with it.
Benbsb, I happened to check out the M5 yesterday again and compared to the Norev Audi A6 and the Kyosho Mercedes Benz E class, the BMW is out of scale. More like 1:19 than 1:18. The paint on the silver one is horrible...terribly horrible. The headlights are all wrong and the grills are really wonky.
Cyrus, your modded car makes the car look definitely better. The silver one I happened to see at Hypercity was pathetic. The paint was uneven and looked like someone had blown the dust off it when it was drying I wouldn't even touch it with a barge pole. So all you potential M5 buyers be aware. I also want to say again that it is undersize and not truly 1:18. Its shorter and much narrower. Maisto had taken one step ahead with its Mercedes CLS model. With this M5, it has taken 3 steps behind.