NASCAR Heat 5

When managing a team go, in the pre-race setup, to the My Teammates tab. With the employee highlighted press to bring up the training tab. Then pick the skill or skills you want to bump up +, make all 3 skills the max value, and pay the price of the training to get the achievement.

The price will depend on what skills the employee already has. Some are virtually unskilled (low skill points, so more expensive to max out) while some are already specialists (more expensive to hire, less expensive to upskill).

Do this in the XDT Series. It will cost you about 600k for everything to buy and upgrade.
each Teammate can be hired for $20 and maxed at about $22k.
The cars cost max. $60k for all 6, starting at 1k, 5k, 8k and so on.
The departments can be maxed for I think $100k?

I've started with $11.2M and ended up at $10.6M after buying and maxing everything in the XDT Series.

I might also add, that I did this in Season 4 after gaining a little bit of money.