we've had like 5 brand new Nissan cars. LOVE them. First 3 were Altimas, then in 2005 I bought a new Maxima. man those cars are fast. But needs 91 octane, and get's about 18 MPG and high insurance even for my old rear. So we had it until March 2008, and traded it in with only 22,000 miles. Got a 2008 Altima with the CVT transmission. Awesome car!
insurance cut in half, lower payments, and gas mileage can be as high as 28-32 on highway. IMHO the 4 cylinder is more than enough, and runs on 87 octane.
Go for the Altima, you'll love it!