Thanks for the comments, guys.
Geoff and Jon, for the Lambo silhouette shot, I set the camera on manual, and cranked the exposure down a couple of stops.
I used a shutter-speed of 1 or 2 sec, if I remeber correctly, and set a couple of pieces of card side by side, on top of the mini-studio, so only a slim crack was between them.
I shone the light through the crack, after moving the cards around until the light hit the car the way I wanted. I had to take a few before I got one that pleased me. I forgot to say (although I'm sure you guys already guessed) I mounted my camera on a tripod.