I have a couple of videos to help earn you some extra XP to help you get to level 50 a bit faster.
At the time of writing, I have not reached Level 50 yet, but these methods are definitely helping to level up faster.
First video is more helpful for those who are just starting out in the game, & the second is my preferred XP farming method, which is to go to examine parts on cars.
First method:
Unlock & use diagnostic tool. These will net you 1XP for each part examined, which is handy when you are starting out in the game, so focus on getting them unlocked as quickly as you can when you are starting out.
Second method:
This method is, in my opinion, the fastest method to farm XP. Examine parts on cars. This works on barn & junkyard cars, but the auctions are the place to go. Go for the better quality cars as they tend to be complete (not missing parts like barn/junkyard cars) & manually examine as many parts as you can. You can examine as many cars as you like in the auctions, but you can only examine each car once, once the auction for that car has ended, you cannot go back to it.
Take note that the more parts a car has, the more XP you'll get from it, so I tend to focus on cars with a lot of parts (for example, V8 engine cars or complex cars like the Nissan GTR). Once you've scanned as many parts as you can, start the auction & leave it (unless you actually want to buy the car) & move onto another car. Rinse & repeat.
Note, I had my "eagle eye" perk fully upgraded to shorten the time needed to scan, but this is not essential. It's still tedious, but just a bit faster. Happy farming.