Did it for 2 years at one of the bigger Nissan dealers in central OH. I couldn't recommend it, at least not highly, to anyone that I liked.
Bobzilla is spot on. There are lifers, who all they know is sales, they're generally good at their job in the eyes of the higher-ups but most of the public that has a clue thinks they're a snake in the grass, because they usually are. Those lifers that don't have a conscience can rake in some money though.
If you do have a conscience, or at least care about your customer, you'll probably treat your customer better, and still be able to make a decent amount of money, even develop a decent customer base, but all of the techs will start to get pissed at you for not selling/up-selling stuff the customer doesn't really need.
Pay scale is another issue, most of us were 100% commission + bonus, I was lucky enough to be salaried + bonus, which was good because I was the latter type, didn't sell fluff, had a lot of happy customers, a good CSI, but didn't bring in the bacon like some of the other cut-throat advisors, and generally had a few techs pissed at me all the time.
60 hours is retarded though. I averaged 48 a week, had Sundays off, a floating weekday off or every 3rd Saturday off. You can ask SWMBO I was generally not a very pleasant person to be around when I got home from work.
YMMV, I learned a lot about the industry, people, and myself. Mostly I learned that I don't care much for people, hard to not like people and be in a customer service job.