Promotions - not all of us work in Corporate America. I work in a non-profit organization that is dependent upon government grants and funding. Everyone works at the same rate when doing the same job. I work side-by-side with those that hold degrees and they are paid the same as myself with college dipolma. That's how it works. Car dealerships, definitely do the research, however, many dealerships have stepped away from the negotiation game. I would suggest if someone is really looking for a good deal, look at pre-owned and stay away from brand new. As for lower interest rate when your credit is in the toilet, no creditor will talk to you or lower your interest. That's why I chose to engage a credit counsellor who brought my creditors down to 0% interest and set up a payment plan. (Canada) It was totally worth the expense.
Really know exactly what you want. For example, I wanted a stick shift vehicle with 15 inch wheels and power NOTHING (in order to save on repairs and to handle the local conditions).
Also know what you DON'T want or don't really care about (things like stereos and fancy wheels cost 2x what it would take to have them added later, and flashy colors get dirty fast) and are EXPENSIVE to match if you need touch ups.
Do the homework and see for yourself. It makes a good bargaining chip when you say "I can have a decent stereo installed later for $400 if they want to bill you $700 for a factory installed one."
Do know the market.
Do know when the model year changes.
DO keep your keys in your control. One of the ways to keep you there is to get control of your keys to keep you waiting. That way you can vote with your feet. One of the tactics used on me was to sneer at my offer -- but I had my keys, so I said that wasn't appropriate and left.
They called me back a few days later apologetically and for $150 over my bid price (covering licensing etc) I got the vehicle I still drive today. (I keep my cars quite a while and make sure they are cared for mechanically.) That was 11 years ago.
Many larger organizations include career counselling as part of the annual review. If yours does, take advantage of this to enlist your current manager in helping you get the kind of experience/exposure that shows you are ready for something more. Also: research shows that men and women differ on the average when asking for promotion. Women tend to wait until they are entirely ready for the next-level job - so that they walk in knowing how to do everything from day one. Men tend to ask for the promotion when they are ready to learn to do the job - so that they walk in expecting OJT. Either approach works - but you'll move up faster if your new positions are "stretch positions".