Boo. Two sets of sprites, one with the burner on, one off. The graphics are all rendered so can be scaled easily, and 32bpp versions are easy to make too.
Well, I've drawn some sprites for a police car -- well, more like resized and heavily modified some excellent freely available graphics for a police car. Anyhow, I'm ok with the results, but I wonder if anyone has any suggestions for improvement; this is after all my first attempt at spriting for a newgrf.
I used the red flash- and water-cycle pixels for the flashing lights, but as was mentioned in either this thread or the other one on emergency vehicles, the water cycle is out of synch with the red flash, and since it doesn't fade to black, but rather to blue, it isn't as easily distinguishable. Still, it looks better than red-only to me. Oh, also there is no company color at the moment, just a somewhat drab grey and blue paint job.
Anyway, attached are the sprites and a test-grf I made in NML. Parameters such as vehicle speed, cost, power, and other such are, of course, for testing purposes only and aren't at all balanced or realistic. The sound effect is also just something I quickly edited in -- I'll likely edit a better siren later.
Unfortunately, I cannot seem to figure out this darned "offset" concept properly, so the car sort of jerks around in some views. The NML documentation didn't seem to have any rules for offsets for the different compass views, so I'm at a loss...
I think this is a fantastic start! I honestly have no quibbles with any of it, even the glitches you mentioned. I would love to see the paint scheme also in white, and in brown. I played with having 1-2 cars patrol in a town without any orders, looked just fine. Especially worked well if you're using the traffic lights newgrf.