Mine was quite easy, my previous car was totaled when someone hit me, still drivable, so I drove it for week while I looked at other cars. I still needed a new car quick though.
I was after the standard cheaper model, I don't need any of the extra stuff you get on the more expensive ones. Second hand ones were just as expensive as new, so I decided to buy new.
On Wednesday evening I went to dealer 1 for a test drive, the salesman (he knew quite a bit about the car, all of it accurate), me and my brother took one out, we got back, I said I was interested but I was going to see another car at dealer 2 the next day (always a good idea to instill competition).
On Thursday evening, I went to dealer 2, the salesman didn't know much about it, but didn't try to lie his way out. My dad and I went for an unaccompanied test drive. We got back, the salesman wasn't around so the manager came over, he asked if I liked it, I said I did, but that I was going to see another one at another dealer (I wasn't, but I wanted an out just in case he tried to pressure sell me).
Then I realise how good a salesman this guy is, he says that it will be the same car at any other dealer and what can he do to sell me a car. This was the second last day of the month and I have heard that dealers try to get numbers up at the end of the month, so I say "how about taking $800 off the price", then he says "how about I take off another thousand". I say "done".
We go inside, he asks what colour, I say white, he looks in the database, the waiting period for a white is two months, my totaled car is being picked up the next day so that's no good. I say I need it quick, he says, put a deposit down now and sign the contract and he'll add a condition in the contract that if he can't find me one in 48 hours, the contract is void (he does and we both initial it). I deposit and sign.
I then go to the finance area to sort out payment, I am paying cash so there's very little paperwork. I purposely never volunteered previously that I would be paying cash, the dealers earn money from the finance deals, I wanted them to think that they might get that from me and give me a lower price.
The next day, Friday, at 10:30 in the morning he calls me and says he's found a car at another dealer, done a dealer swap and has arranged transport for it to his dealership. I get the details and transfer the balance of the money to their account.
This is a really tough weekend

I asked if I could pick it up on the Saturday afternoon, but they needed more time, so it had to be Monday evening. Monday comes round and we go to pick it up, I spend about 10-15 minutes doing my PDI. The salesman are surprised, apparently very few people do this. I sign the delivery papers, take the keys and I'm off.
A day later the salesman from the other dealership calls me, I feel a little guilty telling him that I bought from someone else, he was a nice guy who new his stuff, I tell him I just couldn't pass up the deal from the other dealer, he asks the price I paid and I tell him, I apologise

and we both hang up.