Well white is a great colour, but I strongly suggest looking at the following vanilla sprites:
White with some blue:
apogee_cx.png
shuttle_modern.png
shuttle_modernB.png
Off-white, still 'White':
Conquest_bc.png
eagle_ca.png
falcon_cl.png
hammerhead_dd.png
shuttle_ff.png
shuttle_ffB.png
monitor_ff2.png
White with some yellow and blue stripes:
odyssey.png.
When you look at these under starsector-core\graphics\ships have a look at the actual colours that David Baumgart has used. White? Yes, but variations of yellow, light browns, light pinks.
By adding dirt and such to your ships it helps keep it with the them of the game, these are hard working ships that fly through space dust and asteroids and accumulate a 'not pure white' colour. Certainly you can use shades of grey, but there are many subtleties in achieving the vanilla look by sampling.
And if you're looking for a 'flat top' surface have a look at the buffalo_af.png. You'll notice even in those long white stretches there are sprinkles of red, yellow and dozens of subtle shades of white. And even though the engines looks sort of 'grey' they're actually shades of grey, blue, red/brown and tinges of black at the back .