search the forum..or better browse the forum since the search is still a bit buggy.
you´ll find lots of ongoing discussion about this topic with links to videos and tutorials.
for example here:
hi and welcome here at smcars.
your splinecage is definitely a good start and for most modelers around here the next step would be polygon modeling the body of the car following the splines and use them as a 3D blueprint, which you even can use to snap your verts etc.
As i said this would be...
Well i´m still around and i´m still in contact with exidge, although during summer time all of us probably spend less time in front of our pcs and that´s why things got a bit quiet the last weeks.
cool car and nice progress here.
And i can only second Durons advise about the shader for modelling. In maya you can just use the standard blinn material and it´ll show every single bump and pinch. I love this shader for modeling and hate it at the same time because it´s so unforgiving ;)