Ash, Ash, Ash...
The colour of your covers should compliment and offset the colour of the car.
Purple Golgo with gold motor looked hawt. A midnight purple cover wouldn't have had the same impact.
Gayside blue wouldn't suit at all - too tonally wrong.
I ask this...
What colour are your calipers or other 'hilight' items on the car?
This would be a good colour to match.
Personally, I'd go with a deep red finish on your calipers and engine (similar to an R34 motor) - will stand out against the navy blue and even look good with the green stripe down the side from when you backed into your neighbour's car
You might have a nice car yet.