After it was completely redesigned in 1999, the GMC Sierra has benefited from a few upgrades in 2003. With this occasion, the vehicle received a bolder front end and a few interior modifications.

There were also offered new comfort features which included a new sound system and an optional rear seat DVD entertainment center. Other upgrades were made to the brakes, while the engines were also slightly tweaked to run cleaner.

The entire engine lineup however, remained unchanged and the Sierra continued to be powered by the same units as the old generation.

The 2003 GMC Sierra continues to share the same underpinnings with its Chevrolet Silverado twin, but it’s considered slightly more upscale as it has more luxurious features than its brother.

  • 2003 - 2006 GMC Sierra
  • Year:
    2003- 2006
  • Make:
  • Horsepower @ RPM:
    315 @ 5000
  • Torque @ RPM:
    325 @ 4000
  • Top Speed:
    90 mph


2003 - 2006 GMC Sierra Exterior
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The exterior changes of the 2003 generation can be spotted only by a keen eye and most of them were made to the front fascia which is now more aggressive. The red GMC logo continues to stay planted in the center of the radiator grille while the rest of the body remained mostly unchanged.

Regular-cab and extended-cab models come with either a 6.5- or 8-foot cargo bed. Short-bed models are offered with flared rear fenders or a slab-sided cargo bed.

The extended cab Sierras are fitted with two front doors and a set of smaller rear suicide doors while the crew cab comes with four conventional doors.

The GMC Sierra is available with four wheelbase lengths that range from 119 inches to 157.5 inches. Chassis-cab models, without a cargo bed, are offered in longer sizes, and all of these versions are equipped with dual rear wheels.


2003 - 2006 GMC Sierra Interior
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The interior has also received a few smaller upgrades, but the overall design looks pretty close to the old one. However, Compared to the old generation the materials and plastics were slightly improved and the cab seems slightly more upscale.

The center console is slightly curved toward the driver to offer easy access to the HVAC and audio controls. The instrument panel has an intuitive layout and it’s fitted with two main gauges and other smaller indicators which keep you posted on various vehicles stats.

Fortunately GMC has replaced the old steering wheel with a new one which looks fairly good and has a pretty modern design. There are also offered a few useful steering mounted controls and some useful adjustments.

The regular-cab models can accommodate either two or three occupants on the first row of seats, while the extended-cab models while the extended cab models come with an extra rear bench which offers space for up to three passengers.

The Sierra cabs models that are equipped only with two bucket seat up front come with a center console that flows up into the instrument panel.

The driver’s seat is pretty comfortable and offers adequate support for both short and long journeys. The all around visibility is also part of the first class thanks to the wide windscreen and the generous lateral windows.

Except for the entry levels SL models, all Sierras come with Radio Data System (RDS) capability and can work with XM Satellite Radio. There is also available an optional rear-seat DVD entertainment system with wireless headphones. The superior trim levels come with a six-way power driver’s seat, GM’s OnStar communication system and leather seats.

Engines and performance

2003 - 2006 GMC Sierra Exterior
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Except for a 6.0 liter V8 unit which comes with 325 hp on tap, the GMC Sierra’s lineup is identical with the one from Chevrolet Silverado.

The regular cab models are equipped with a standard 4.3 liter V6 unit which develops a maximum output of 200 hp. The Sierra is also keeping the old 4.8 and 5.3 liter V8s which develop 275 and 285 hp, respectively.

The engines can be mated on either a five-speed-manual or an optional four-speed automatic transmission.

The GMC Sierra 1500HD is fitted with a 6.0-liter V-8 engine that develops 300 horsepower and is fitted with a four-speed-automatic transmission. The Sierra 1500HD Crew Cab pickup has a 3,094-pound payload and can tow a maximum weight of up to 10,200 pounds.

Sierra 2500, 2500HD and 3500 come with a standard 6.0-liter V-8 engine that produces 300 horsepower and 360 pounds-feet of torque. These models can be equipped with either a four-speed-automatic or five-speed-manual transmission.

If you want extra hauling capacity you can equip the 2500HD and 3500 model with a stronger 8.1 liter gasoline V8 unit which churns out 340 hp and 455 lb-ft of torque. These engines can be combined with a six-speed-manual gearbox or an Allison 1000 Series five-speed-automatic transmission.

Ride and handling

2003 - 2006 GMC Sierra Exterior
- image 467702

The GMC Sierra offers a good balance between comfort and utility and its suspension is pretty forgivable. The handling is also pretty predictable and the truck stays well planted on its wheels with the body roll perfectly kept in check.

The rack and pinion steering is pretty accurate and you can rely on it with confidence at both high and low speeds.

The old standard all-around disc brakes have been upgraded and the stopping power continues to be among the best in the segment.


2003 - 2006 GMC Sierra Exterior
- image 467704

The old Sierra was one of the most capable pickups in its segment and the 2003 generation continues to keep the standards high. The exterior changes however are pretty limited and the truck’s style remained a half step behind its rivals.

The cabin has also been revised, but the overall design remained mostly unchanged and continued to have a dated feel.

Except for a few minor tweaks, the engines lineup was carried over from the previous model, which isn’t exactly a bad thing, as all units are fairly capable of dealing with the utilitarian character of the Sierra.

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