With more than 9 million units sold in 50 years of continuous production, the Ford Mustang has little to prove to fleet buyers, pony car enthusiasts or anyone else.

But the all-new, sixth-generation 2015 model is dressed to impress with new exterior and interior styling, new front and rear suspensions, bigger, more powerful brakes and a four-cylinder engine option.

The four-banger slots between the base model’s 3.7-liter V-6, which delivers 300 horsepower (hp) and 320 pound-feet (lb.-ft.) of torque, and the Mustang GT’s 5.0-liter V-8, which is good for 435 hp and 400 lb.-ft. The new engine uses every available means, including a turbocharger, direct injection and variable cam timing, to eke 310 horsies out of a 2.3-liter stable.

Paired with a six-speed manual transmission (all three engines can also be mated to a six-speed automatic), the EcoBoost I-4 earns a combined fuel economy rating of 26 miles per gallon (mpg). That’s an impressive mark for a segment that also includes the Mustang’s longtime rival, the Chevrolet Camaro, as well as the Dodge Challenger and Hyundai Genesis Coupe. It should be noted that the Challenger achieves a combined rating of 23 mpg with a bigger, badder V-6.

All three engines have won the hearts of critics, who have heaped praise on the new ’Stang’s starts, stops and handling. The front and rear suspensions are now fully independent and enhanced by a finely tuned traction control system and an adjustable electric power steering system, which offers Standard, Sport and Comfort modes.

The exterior features a slightly wider and lower stance, a more rakish tilt to the front and rear windshields and extended side windows designed to improve blind-spot visibility. The Mustang’s signature shark-bite grille, long, sculpted hood and three-bar taillights return. Opting for the convertible adds $5,500 to the sticker for a V-6 or V-8.

A dual-cowl dashboard and aviation-inspired gauges, dials and switches dominate the cockpit. The backseat is still very small, but the new trunk is big enough to hold two golf bags.

The 2015 Ford Mustang is in showrooms now. MSRPs start at $23,800 for the base 3.7-liter and top out at $46,170 for the 5.0-liter GT.