I didn't know that! Which tracks are they based on?
Speedway 2 I can't remember
Mixed 1 - Kaanaa (Finland)
Mixed 2 - Valkenswaard (Netherlands)
Tarmac 3 - Vålerbanen (Norway)
Mixed 4 looks like inspirational Estering. The general layout is the same even though scale and details are pretty different.
Mixed 5 is likely based on some real life location but the track is fictional. I base that assumption on the reason that there's so much satellite texture and height map around the area that isn't used. Though likely many tracks are based on some real life location and then the tracks has been just made in there.