Hi there - your grasp of the photo mode seems absolutely fine from what I see. Night time is notoriously tricky and the pics in your second post are good. First step for finding where to get a good picture is saving a replay. Some work from the game, just pausing it, getting the photo mode parameters they want and capturing the shot. I prefer working from a replay as you can watch it for likely moments and even rewind if you miss a particular angle. The only trouble with that is Driveclub has certain dynamic factors which respond to the game engine and so will be different each time you view it - for example: a swirl of petals or leaves might look superb the first time through, but the dynamic wind will present you with a different pattern of petals/leaves if you rewind and re-run the sequence. Lighting too can be different if you have it set to anything other than dry and clear: but it'd be no fun if it wasn't at least a bit difficult to capture what you want
As for filter choice etc., that is something which is personal. Some can make certain filters do almost anything, whilst others shun them like the plague. I think the point is, work through the possibilities of each filter (strong/weak saturation, light and dark, overlays and see what you get. Time will teach you which filter is best for which lighting conditions.
Don't forget 'depth of field' (DoF: how much of the picture will be in focus and where the focus lies) or the 'field of view' (FoV: from fish-eye to extreme close-up, determining how much is to be included in the picture.) These two tools alone can make a picture completely different.
If you wanted to read up on the technical aspects of gaming photography, both the GT5 and GT6 photo mode forums have fairly lengthy explanations available stickied somewhere near the beginning. Okay, they're designed for different games but the camera part is valid for DC too.
Good luck.