Yep. All with the D3100 and the cheap 35mm 1.8. You can always view my EXIF data on my flickr (all pictures on there are shot with the D3100 and either the 35mm or the 85-200 which is also affordable) to see how I got these pics.
MAJOR thing to keep in mind is that the D3100 STINKS at low light auto focus. So you may want to practice with manual as much as you can. I get a lot of blurry pics..yes..but as you can see above, once you zero in..it can do great.
Also..in dark rides...to start I'd say shoot in Shutter Priority to get your feet wet...then as you get more comfortable..move on to manual. I always shoot as wide open as I can (in the examples above, that usually means 1.8), and at a high ISO (3200 which explains the grain). I do some post processing to remove SOME of the noise (I will get arguments about this, I'm sure...but the Noise from a Nikon is a LOT more manageable than the noise from a Canon), and then as long as you aren't printing large format..you don't notice