Although the company won't reveal the cost, the list of changes is extensive.
The project redesigned Sentra's front end from the A-pillar forward. It installed higher-end safety features, including forward emergency braking, adaptive cruise control and blind-spot warning. It restyled the interior, adding more advanced connectivity hardware and a beefier steering wheel, and it re-engineered the suspension and steering system to make the car quieter and give it smoother handling.
In all, 20 percent of the Sentra's parts are new for 2016.
Why lavish so much attention and expense on the Sentra just three years after the current generation's debut?
"The segment is incredibly competitive," says Ken Kcomt, Nissan's director of product planning for passenger cars and sports cars. "The competition is very aggressive and we have to stay ahead of it."
But Nissan also wants to make sure consumers new to the brand get a Sentra that squares with what Nissan has been doing to raise the appeal of its larger and more expensive products, such as the Altima midsize sedan and Rogue compact crossover.
"A lot of people first come into Nissan through the Sentra," Kcomt explained at a press event here. "They might be a young couple buying their first new family car, or they might experience it renting a car on vacation from a daily rental company.
"We want to make sure they like what they're experiencing, especially with comfort and quietness, and with the technologies they find."
Compact cars make up a large part of the U.S. daily rental fleet, and the Sentra is a key player in that business.
The company does not intend to increase Sentra sales to daily rental companies, but will hold at about 15 percent of the nameplate's volume.
Last year, Nissan sold 203,509 Sentras in the United States, up 11 percent from 2014.
U.S. sales of the Sentra have nearly doubled since it was redesigned for the 2013 model year, and Nissan believes sales of the freshened Sentra will grow.
The midcycle changes were directed at what a consumer senses immediately -- including a front-end redesign to get the signature V-motion grille and boomerang-shaped headlights to match the looks of the Maxima sport sedan.
The 2016 compact is also quieter, thanks to more insulation in the floor, doors and dash, and the use of a laminated-glass acoustic windshield. The ride has become more solid due to retuned springs and dampers, changes to the engine mounting and other chassis refinements.
Inside, the Sentra gets Apple's Siri Eyes Free driver assistance technology standard on most packages. Nissan refers to the Sentra's redesigned steering wheel as "Z-inspired," alluding to the heavy-grip performance steering wheel of the 370Z. The driver receives a six-way power seat with two-way power lumbar support. The rear seats are generous for the compact segment.
"It was important despite all this to keep our prices at the same level," Kcomt says.
The 2016 Sentra is in showrooms with a base price of $17,615 on the S model, including shipping. The SL price is $23,005, including shipping. The popular Sentra SV with Siri Eyes Free and a driver assist package that includes navigation, blind-spot warning and rear cross-traffic alert retails for $20,405, including shipping.