SIMILAR NOISE
I just bought my 2.5 SL about a month and a half ago, and I too noticed the engine noise. It is an annoying engine sound that I only hear when the car is idling. I don't hear the noise if I am standing outside the car, or when the car is at cruising speed. I attributed this noise to the fact that the car is a 4 cylinder, and that the engine noise was one of the biggest complaints written about the car in a lot of the automotive magazines. They described the engine as unrefined, and very noisy, but despite the negative press, I liked the car when I test drove it and bought it. They actually commented about the engine noise that the V6 produced as well, but they raved about the HP. So I guess the authors figured it was a wash. A little bit of noise, for a lot more juice. My previous car was a Saturn SC2 that was also a 4 cylinder, but that engine was very quiet when it was running well, but didn't have nearly the HP as my new Altima. Judging from the replies to the original post of this problem, I'm begining to think that this engine noise is not normal, and I better take the car in to have it checked. Thanks