I worked at a CarMax, Ford and a Toyota dealer. CarMax is not your traditional dealership, so you don't have to BS your customer. At a dealership you will BS your customer and the hours are LONG! Bell to Bell - usually 8:30 AM until 9:00 PM. The first thing they will tell you is that you will have 1 or two days a week off and you should take them to re-group yourself. THEN they will tell you that if you take those days off, you will NOT be making money!
Training at most dealerships in non-exsistant. They will stick you with a "seasoned" veteran to learn the ropes. That will be good for a few hours, then you will be cramping his/her style and they will give you some books to go read, so you can learn about your product. This "training" period will normally last 2-3 weeks and you won't be seeing any customers. The dealership will have you on salary until your learning curve is over, then it's straight commission.
What ever you do, please don't think that you will be selling every car on the showroom floor. It just won't happen. Your first sale will most likely be a MINI-DEAL - and that is only after a week and a half. Mini deals are almost bear minimum profit for the dealership and you will be getting $50-100 for all the time you spent on it. Then you will have to give your mentor 1/2 of it for his expertise he gave you. Other sales people are LYING to you when they say they make $100k a year. It's maybe one out of 500 that make that kind of money and they are NOT working at a domestic dealership, BMW, Audi, Lexus maybe, but at a Ford, Dodge or Chevy store - NO.
Get used to customers treating you like dog crap, because to them, that is what you are. Car dealers rank right down there with lawyers, but the later makes a whole lot more money. Get used to your managers treating you like dog crap, too, because if you are not selling, then you are totally slacking off and not making the dealership any money, thus the manager is not making any money!
Your co-workers are not there to be your friend. They are there to make money, and money only. Make sure you document every single contact you make with a customer, because if not and another sales consultant sells them a car, you are TSOL (Tough Sh*t Outta Luck).
Hope you don't mind smokers and drinkers. Not your customers, but your co-workers. 95% of all sales reps are smokers and drinkers. And you will find some of your co-workers half drunk while they are there.
I could go on and on about the bad parts of being a car sales person, mainly because there are not very many good parts. Again, long hours, disrespect, low pay and no time off. I spent over 5 years in the business and the best day of it all was when I turned in my resignation so I could work in electronics!
I hope this doesn't put a damper on your choice of jobs, but it is not a glamorous or money making job. I know, my best year I made about $35000!