Thanks for the advice.
It was a last minute thing especially given the lack of sleep I got the night before and my flash batterys were flat (although I could have used in inbuilt flash a bit).
in a few pics I did paint with the car in light with a tiny LED torch I keep in the glove box.
I wouldn't have used much more flash in the first picture, I think that shadow adds to the effect.
I would have got more pics of cars going past but at 3am there was a distinct lack of traffic on that road
I got my mates g/f to drive her skyline up and down the road 3 times but i'd have felt guilty if i'd made her drive up and down the road again and again while I got things right. After all i was meant to be there helping a mate take pics, not the other way around.
I'd love to take longer exposures and reduce the aperture but I don't have a remote yet so the longest exposure I had was 30 seconds. The first and probably others I had to open it right up just to get enough light.