It was requested in the latest little dev update, so here you go, I'll get started.

Finance:
Financial tree that improves loans, streamlines admin costs, and generally lets you get more buck for your bang.
-Loan negotiation: A flat bonus to how much you can cover via loans, on top of the normal percentage amount.
-Risk mitigation: Allows a greater percentage of project cost to be covered by a loan.
-Lobbying: For the company's home country, reduces penalties for not meeting emission standards, grants a grace period on safety regulations, and reduces various assorted costs a bit, representing things like tax breaks.
-International lobbying: Same as lobbying, but for all other countries, with somewhat lesser effects until the final, very expensive tier (few companies can manage to get their fingers in the pie in every major country).
-Offshore sourcing: Reduces costs on low quality parts, with effects diminishing as quality increases (low quality parts can be made offshore with cheap labor and materials, but high quality parts don't cost much less no matter where they come from).

Personnel:
A tree which allows you to get more out of your people, and/or have more of your people. It could be organized into two sub-trees, one primarily focused on factory workers, the other on HQ staff.
-Hiring incentives: Makes it quicker to fully staff a factory.
-Employee benefits: Makes it easier to retain higher quality workers and improves engineering expertise gain (basically, helps retention).
-On job education: Allows worker quality to improve with time (if there's simply not enough good ones on the market, hire poor ones and train them).
-Agile development: Improves engineering times by implementing modern management techniques.

Marketing:
Influences brand prestige and advertising campaigns.
-Product placement: Gives a passive brand recognition boost across the board.
-Company cars: If the company makes any of the "daily driver" cars, improves brand recognition and employee retention/quality by incentivising them to drive one of the company's products. If the company only makes less practical designs, the effect is lessened.
-Motorsports sponsorship: Improves company prestige gains from performance numbers.
-Tie-in luxuries: Improves prestige gains from high comfort and prestigious components.

Reliability:
Affects recalls and reliability events, as well as the used car market.
-Repair-friendly engineering: reduces the cost of recalls, the cars' service costs and makes them last longer on used market.

Perks in no particular order, though some are fairly obviously progressions from one to another. That's just a few ideas that I had right after I watched the video, so they might not be well balanced, but it's a start.