Your best bet for a quick and easy level up is to go at the road event at the south roundabout of the highway and look for a blueprint with a clickbait title and more than 1 lap and do it. What you want is a few laps of going up and down the highway. It'll be quick and easy cash because the maker will have made the AI go through slow places on purpose. (XP and Money you earn depends on how long the race lasted, not how long the track is. If you complete a 50km race in a few seconds because the author put the finish line right beside the start but made the AI go around the map, you'll get nothing because the race time was short).