Yes it is vital to do research prior to looking round. I turned up at the dealer, they had a car on the forecourt that was ideal for me. I had a trade-in and needed finance. I knew what I wanted to pay, which was about 150 notes a month less than the salesman's first offer. Through negotiating the trade-in value of my old car and the interest rate on the finance, together with a subtle giggle when the screen price of the new car was suggested, a mutually acceptable deal was thrashed out.
It was nearing the end of the month and the salesman may have been short of his target. It felt too easy.