Across most of the 2010 Nissan Altima Coupe and sedan models, you have a choice of a four-cylinder or V-6 engine. The 2.5-liter four makes 175 horsepower and does just fine either with the six-speed manual (coupes only) or the Xtronic CVT automatic (both models).
Under the hood of SR models is a 270-horsepower version of Nissan's well-regarded 3.5-liter DOHC V-6. With the V-6, the Altima feels refined and strong in either body style—although there's a little too much torque at times for the Altima to deliver smoothly through the front wheels. Car and Driver testers post some of the best acceleration times in their Nissan Altima 3.5 SE, "getting from 0 to 60 at 5.9 seconds" on the stopwatch. Edmunds says "strong performance from the V6 models should more than satisfy those who like a kick in the pants when they boot the gas."
In terms of the lower-output four-cylinder on the Nissan Altima 2.5, there are still plenty of positive terms thrown around. ConsumerGuide asserts that the "conventional 4-cylinder models" are "sprightly from a stop and show good highway passing response," and they rate the 2009 Nissan Altima 2.5 S above the class average in terms of acceleration. "The four-cylinder models aren't particularly quick when pushed hard, but the V6 pulls strongly, with a broad power curve that makes it easy to breeze past slower-moving traffic," reports Popular Mechanics.
The CVT works better than most, even with the four-cylinder, with revs settling down to an economical level at cruising speeds, and revving higher when accelerating, yet avoiding the uncertain rubber-band feeling that some CVTs have. Cars.com considers it "about as good as they come in terms of responsiveness." Less pleasant is the Nissan Altima's six-speed manual, which Edmunds blasts for its "abrupt" clutch engagement and a shifter that "feels unsubstantial." Car and Driver writers agree, noting "the shifter clunks through its prominent detents," making the Altima "no BMW in this regard; no Honda, either."
The Altima Hybrid gets an advanced full-hybrid system with the 2.5-liter engine, tuned down to 162 horsepower for improved efficiency; altogether the hybrid system makes 198 hp. That power reaches the road through a continuously variable transmission, via the front wheels.
ConsumerGuide feels that "the CVT in this application slightly dulls passing response." However, they call it "generally strong" in most driving situations. Automobile Magazine reviewers note that "slow, fluid starts and a gentle application of the accelerator pedal can keep the Altima running off electricity at speeds up to 40 mph."
Like all hybrids, the 2009 Nissan Altima Hybrid boasts commendable fuel economy ratings. According to official EPA estimates, the Nissan Altima Hybrid should return 35 mpg in the city and 33 mpg on the highway—significant improvements, especially over the base Altima's 23 mpg city rating. Cars.com states that some of the other fuel-saving measures include a feature by which "the four-cylinder engine shuts off when the vehicle comes to a stop."