I started a completely new profile at 9 and within three hours, I'd leveled up to 21 and had 2 million in the bank. I started out with a used Nissan, threw a few upgrades on it, did three quick races on the Autumn Ring to get to level 1, did the level 1 karting challenges, the level 2 Nascar stuff, the Top Gear samba bus challenge, bought a Mazda, upgraded it to 500hp, did a three lap race on Tokyo r246, then did the 10 lap 600,000 credit event at Tsukuba, bought an Elise, upgraded it, did the 500,000 credit challenge at Nurburgring G/P, bought a Ford GT, upgraded it to 800hp, did the 5 lap/1 million challenge at Trial Mountain, then bought the Citroen road car for the 1.5 million event at Rome. So the A-spec grinding from level 0 to 21 has been eliminated.
edit: I went this route to get enough money to buy an exotic, then gift it to my main account. (shrugs) it was more interesting this way than doing that fucking boring Indianapolis 500 challenge in the American Series.