That's normal.
If you're not using any photo editing software, you need to make them brighter before you shoot them, usually between +3 and +6, but it depends a lot of the track you're in, what car you're using, where the light is coming from... Takes some practice, trial and error.
If you don't have any editing program, try to download GIMP, I've never used it, but it's free and some people here have brilliantly edited shots using it.
And another thing, don't post many pics on every update, try narrowing it down to just the best. It will also help you separate what's good and what's not, and you'll improve by doing it.
Apart from being dark, your shots aren't bad at all. 👍