NASCAR The Game 2011

I ended up grinding most of this via career. Just before going into the last race of the season at Homestead, replay the available Martinsville race. I found that 50 lap races worked best for me. This minimizes game load times, and time spent doing qualifying laps.

Why this works so well is that you can rack up tons of points in the race for.
Leading Race - 250 per lap
Dominating - approx.200 per lap
Fast Lap Times - 50 per fastest lap
Passing/Lapping Cars - 30 per pass/lap
Drafting - ?? Not sure as this is really up to you.

In a 50 lap race, this all adds up fast so 20,000 to 30,000 NXP is the norm. What is really nice about this is that by this point in the game you should have all your sponsors so their Sponsor Bonus adds another 14,000 plus NXP to the race. Still try to get a good end of race burnout as all points are important when grinding.

Repeat this a few times and you will be at level 30 in no time at all.

you need exactly 841,000 NXP to reach level 30.

I cannot add to the solutions, because these are the best methods, I just wanted to add the exact amount of NXP you need for reaching level 30 to put things into perspective for you, and you can see JUST how much grinding you will have to do.

On a personal note, I combined these methods to an extent. I would set up a 50 lap race on Bristol, and then race around and draft the 43rd place car. Not only are you getting 250 points for leading and 100 points every 15 seconds for dominating, but you are picking up points for drafting. If you finish up first, you can abuse the burnout as well. Might make things less boring for you !

I made a video showing the way I got to level 30. There may be faster ways, but this is how I got the achievement. I started a single player race on Daytona and drafted the AI car to rack up some nice NXP. Hope it helps cut out some of the grinding time needed for this achievement.

Also put laps to 2 so you can work towards the "win 200 races" and "100 fast laps" achievements while you're getting to level 30.

This Achievement is a grind so be warned. I beat all the events on their minimum lap length and only got to about level 20, I got from level 20 to 30 using this strategy: The most efficient way to earn NXP and reach driver level 30 is to do the following:

Go to single player from the main menu, select your favorite driver, then go to "Race Now", select Martinsville as the track.

When prompted, put the opponent difficulty on easy, the number of opponents on 1, the number of laps on 2, put qualification off, tire wear and fuel off, damage cosmetic, caution flags off, then press A

When prompted , put all the assists all the way up and put AB (auto brake) on, then press A

The race will only last about 45 seconds, when you win begin your burnout imediately hold A and X (or LT and RT)) at the same time, you will earn about 1400 to 1600 NXP with each burnout and over 3000 NXP total each race this way. When the race ends hit race again...Rinse and Repeat...3500 NXP every 2 minutes or so.

The solution I am presenting is very similar to what Evil Brett Deez said, however a different method to help you stack up NXP in ONE race. Also, go to Martinsville, select a FULL 500 lap race, 42 opponents, difficulty set to easy, and turn yellow flags, fuel/tire consumption, and damage off. It should be REALLY easy to lap every car (multiple times), and THIS is where the NXP comes in:

Every lapped car gives you 30 NXP, leading a lap is 250 (125,000 NXP for leading every lap), and dominating (usually given twice a lap) is 100 each (200*500 = 100,000 more NXP). Leading every lap, lapping plenty of cars multiple times, leading all 500 laps, and getting a "dominating" bonus twice each lap should give you a TOTAL of 250,000 NXP earned that race. It should only take about 3.5 hours to do. If you repeat this 2 more times, you should be able to reach rank 30. Good luck!