1989 GMC S15 Sierra Classic (Specs and Features)

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The 1989 GMC S15 Sierra Classic represents the beginning of the most popular and reliable compact pickup trucks with impressive specs and features.

Around the same time, GMC introduced both the GMC S15 and S10 to compete in this compact pickup truck segment. It took a while for this vehicle to find its identity and stick with one name, and the 1989 Sierra Classic model is one example of excellent payloads, fuel efficiency, and performance on a budget.

This 1989 GMC S15 is a compact truck with a standard high-performance V4 or V6 engine. Multiple trim levels were released, including a regular cab with a short box, a regular cab with a long box, and an extended cab with a short box. The design included plenty of heavy-duty features too.

The most notable features of this truck include upgraded exterior lights, bumpers, and grilles that were renovated for this renewed first-generation release. For performance, a new two-wheel drive package was included in three different body colors. Overall, this truck has a lot to offer, and this guide fully reviews the specs and features.

The 1989 GMC S15 Sierra Classic is the perfect vehicle for those who want to be able to haul gear or cargo around in comfort and style. We have gathered all key specs directly from GMC, so this guide is as accurate as possible.

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1989 GMC S15 Sierra Classic (Specs and Features)

The 1980s was a decade of excess, with larger-than-life hair, flashy colors, and over-the-top fads. At the same time, the 1980s was also an era of smaller cars that were fuel efficient and practical for drivers who didn’t have much room in their garages.

GMC introduced its S15 Sierra classic truck in 1982 to serve this market segment. It featured a small body and V6 engine with plenty of torque for hauling or towing capacity.

The first generation of GMC S15 Classic trucks produced between 1982 and 1993 is called the first generation models, and they ran under multiple names like the GMC S15 or GMC Sonoma.

The GMC S15 is one of North America's most popular mid-size pickup trucks because of its reliability and durability. It was first marketed as the quarter-ton pickup until it took on the S15 nameplate.

Without knowing the key features and specs, you’ll fail to realize how reliable this truck truly is. Keep reading to learn what it can offer.

1989 GMC S15 Sierra Classic Features

The 1989 GMC S15 Sierra classic trucks were equipped with a 4.3 Liter Vortec V6 engine that was an upgrade from the 3.8-liter V6 engine used by the GMC S15 Classic.

This V6 engine featured a computer-controlled fuel injection system with a sequential port fuel injection system (SPFI) producing 92 horsepower. You can expect enough power for most towing and hauling tasks.

This inline-6 engine also comes with a 4-speed automatic transmission. It also has front disc brakes and rear drum brakes. The GMC S15 Sierra Classic had a ladder frame, and its wheelbase was increased too.

Below are all of the best features, and we also explain the different trim levels and whether this vehicle is worth buying.

Engine Type

The base 1989 GMC S15 Classic engine was a 4.3-liter V6 engine with an SPFI fuel injection system. This engine produced 160 horsepower and 130 lb/ft torque.

Peak horsepower was achieved at 4,600 rpm, while maximum torque was achieved at 2,800 rpm. You could also opt for a less powerful and cheaper engine type for simple daily driving needs.

The optional 2.8L v6 engine comes with a fuel-injected throttle body available in the 1989 and 1990 model years. This engine produced 94 horsepower and two-wheel drive capabilities.

Fuel Efficiency

The GMC S15 Sierra Classic is one of the better trucks for fuel efficiency, but it's not without its drawbacks. It only seats four people, has no navigation or safety features, and only comes with multiple transmission options.

On average, you can expect fuel efficiency between 17-22 MPG depending on the engine, model type, and transmission. Vehicle size also has an impact.

Below is a chart with a breakdown for each available trim level with the corresponding MPG based on these factors.

Model Type Transmission Engine Type Fuel Efficiency
2WD Automatic 4-spd 4 cyl, 2.5 L 21 MPG
2WD Manual 5-spd 4 cyl, 2.5 L 22 MPG
2WD Manual 5-spd 6 cyl, 2.8 L 19 MPG
2WD Automatic 4-spd 6 cyl, 4.3 L 18 MPG
4WD Manual 5-spd 6 cyl, 2.8 L 18 MPG
4WD Automatic 4-spd 6 cyl, 4.3 L 17 MPG


When buying the 1989 GMC S15 Sierra Classic, you can expect two options on most models for a transmission. This includes either an automatic 4-speed or manual 5-speed transmission type.

It will vary based on your exact trim level and engine type. However, there are plenty of options available today that have been renovated to include a more modernized transmission type too.

Interior Design

One of the most distinctive features of this vehicle is its boxy shape with a forward-slanting rear window. This body style became popular with truck buyers and set the trend in the industry.

The interior in all trim levels included bench-style seating and only three seats for a driver and two passengers.

Its standard features include an AM/FM stereo radio with CD player, power windows, power locks, power mirrors, dual airbags for front seat passengers, and side curtain airbags for rear seat passengers

Exterior Design

This Sierra classic truck features a box-type frame with closed-box frame rails, front and rear rubber bumpers, and a rear-hinged single-side door.

The truck bed featured a locking tailgate and a gas-charged shock-absorbing suspension for hauling heavy loads. The Sierra classic featured a unique grille design and GMC emblem, as well as body-color bumpers, door handles, and running boards.

It’s notable that this year was one of the keys to this entire first-generation vehicle because of the renovations to the exterior. It was one of the first major facelifts for the S15 truck.

1989 GMC S15 Sierra Classic Trim Levels

The Sierra Classic has been a popular model for over two decades. The Sierra Classic has numerous trim levels to choose from, which makes it one of the most customizable trucks on the market.

Below is a chart with each trim level type and the corresponding engine and transmission. This allows you to see which option includes what to decide on the highest performing model for your needs.

Model Type Engine Type Transmission Fuel Efficiency
Special Reg. Cab Short Bed 2WD 2.5L L4 OHV 8V Manual 5-spd 21 MPG
Ext. Cab 2WD 4.3L V6 OHV 12V Automatic 4-spd or Manual 5-spd 22 MPG
Ext. Cab 4WD 4.3L V6 OHV 12V Automatic 4-spd or Manual 5-spd 19 MPG
Reg. Cab Short Bed 2WD 4.3L V6 OHV 12V Manual 5-spd 18 MPG
Reg. Cab Short Bed 4WD 4.3L V6 OHV 12V Automatic 4-spd or Manual 5-spd 18 MPG
Reg. Cab Long Bed 2WD 2.5L L4 OHV 8V Automatic 4-spd or Manual 5-spd 17 MPG

Special Reg. Cab Short Bed 2WD

The Special Reg. Cab Short Bed 2WD is a truck with tons of features and an affordable price tag. It has a classic look that is sure to turn heads and make you stand out from the crowd.

It comes with the traditional manual five-speed transmission and 2.5L L4 OHV 8V engine type. This is a good pickup truck that has the power to go anywhere. It’s also the perfect vehicle for those who love going off-road.

Ext. Cab 2WD

This trim level had the same engine as the base, but it also had an automatic transmission and two-wheel drive option. The primary difference is the larger cab, so you can expect an increased wheelbase and vehicle length.

This helps for those with larger cargo loads or heavier payload requirements. This is the cheaper option compared to the 4WD extended cab model too.

Ext. Cab 4WD

The extended cab 4WD trim level came with a 4.3L V6 engine with a 5-speed manual transmission or 4-speed automatic transmission and all-wheel-drive. This means better stability for winter driving.

The one downside to this truck is the reduced fuel efficiency of around 18 MPG. The interior also included only three seats like all other trim levels despite the increase in size.

Reg. Cab Short Bed 2WD

The regular cab short bed 2WD trim level is less impressive in terms of size because of the reduced-sized bed. However, it’s a more practical option for daily driving for most drivers.

It’s much easier to handle, and the stability is reliable. You can also expect the best fuel efficiency but poor winter driving performance compared to the other trim levels.

Reg. Cab Short Bed 4WD

This trim level has everything the 2WD model above offers, but improved driving and handling efficiency. It’s the preferred choice for drivers who aren't as confident driving a larger truck but need a winter vehicle.

Reg. Cab Long Bed 2WD

Lastly, you can consider the regular cab with a long bed and 2WD capabilities. We like this option if you are on a budget but need a larger bed for work reasons.

The payload capacities were improved, and it provided a more powerful feel on the road. But you shouldn't expect anything but average winter driving performance.

Is The 1989 GMC S15 Sierra Classic Worth Buying?

The 1989 GMC S15 Sierra Classic is worth buying because it has many features still in use today. It has an automatic transmission, rare for pickups from that time period, and a 3.8-liter V6 engine.

It also has many features that are no longer in use, but the truck still looks good today because of its classic design and features like dual rear wheels and full-wheel covers.

You can expect extended mileage on these trucks, and the cost only continues to drop. The average retail price is well below $5,000 for a reliable, heavy-duty pickup truck.

How Long Will A 1989 GMC S15 Sierra Classic Last?

A 1989 GMC S15 Sierra Classic is a truck with a lot of potential and will last long. It is an older vehicle, but the engine is still going strong, and the vehicle will continue to serve you well.

This truck engine can run strong for over 25 years. The truck is also known for its reliability and durability, with an estimated mileage of up to 300,000.

How Does The 1989 GMC S15 Sierra Classic Compare To Other Similar Trucks?

The 1989 Sierra Classic has plenty to offer, as discussed above. But the trucks from this era are all different from each other and have their own strengths and weaknesses.

Below are some of the best alternatives if you find flaws in the GMC S15 and want to try something different.

1989 Dodge Dakota

One of the main competitors for GMC in the 1980s was Dodge and the Dodge Dakota. The 1989 model was one of the first generation releases, and this truck has plenty of features.

The Dodge Dakota has a front-wheel drive configuration, with a longitudinally mounted engine and gearbox, in contrast to the rear-wheel drive configuration of most pickups.

Overall, this truck didn’t provide the same type of power as the S15, but it had much more versatility and variety. There was even a convertible model released during the 1989 production run.

1989 Jeep Comanche

The 1989 Jeep Comanche was first introduced in the year 1985. It was discontinued in the year 1993, but it was considered a classic because of how unique it was.

The Comanche had a single cab with an open bed, which could be fitted with a variety of cargo boxes and roof racks. It also has some tough off-road capabilities, thanks to the limited-slip rear differential and front and rear sway bars.

The 2-door design was compact, and there were multiple engines and transmission options. On average, you could expect around the same horsepower and performance as the S15 but with much less durability.