Get a car, go to the sand dunes at the side of the airport, do drifts and jumps and drive over the bushes and you get more than this in a shorter time.

Go to one of those fields and drive though all the small tree's drifting around, also a better method.

Go to the redstone gold mine bucket list blueprint, find the one by Don Joewon Song, drive the Bugatti up to 284mph, takes less than 2mins and you still get more ultimate speed skills than you would from your method in shorter time.

Get Byron bay to level 5, grind the Goliath race (takes no more than 10 mins), get around 60 to 70 thousand xp, 5 or so skill points per race and 70 thousand credits or so (more if you have a Horizon edition skill/XP/credits boost car) and lots of fans.

But to be honest once you've unlocked a few of the perks it becomes really easy after that anyway, driving up and down the airstrip in a straight line is stupid.