Utility trucks are just like any other business item–their value is weighed based on their return on investment (ROI). However, achieving a good ROI for conventional-cab trucks can be tricky–not only are they expensive, but most models also have high fuel consumption and costly repair needs.

This is why truck owners and drivers alike rejoiced when Kenworth introduced their T660 model in the market. Kenworth promised excellent fuel efficiency–and they didn’t disappoint.

In this article, we’ll take a look at the history of the Kenworth T660 and why it is hailed as one of the most efficient and profitable conventional cab trucks introduced to the market.

History of the Kenworth T660

To understand the development of the Kenworth T660’s overall design, we’ll review its history and development. 

1976 Kenworth T600

Undoubtedly, one of Kenworth’s most well-liked conventional-cab truck lines is the T600. The T600 was the American market’s first semi-tractor created expressly for high fuel efficiency. This will not come as a surprise, though, as the T600 is Kenworth’s response to the 1973 oil crisis, which significantly increased diesel and gasoline prices.


1976 Kenworth T600

The Class 8 T600 had an aerodynamic sloped hood, set-back front axle, smaller turning radius, longer front springs for better suspension, and improved weight distribution. All these bodyworks made T600 units 20% more fuel efficient than the famous W900 and other Kenworth models. Furthermore, the lower drag design enabled the T600 to run with approximately 100 less horsepower despite full payload, further increasing its fuel economy.

Due to its popularity among businesses, Kenworth continued developing numerous variations of the T600, increasing fuel efficiency with every update.

1990 Kenworth T600A and 1995 T600B

Before moving on to the T660, Kenworth released two sub-variants of the T600. The Kenworth T600A, introduced in 1990, shared the T600’s general interior and exterior. However, it also had brand-new rearview mirrors mounted in a single housing, a twin-segment grille, and curved windshields. The Aerodyne Sleeper Cab II, which first appeared in the W900 range, was its basis. 


Kenworth T600A from the 90s

During this time, Kenworth partnered with Boeing, giving some T600A units a digital dashboard. 

In 1994, the Kenworth T600B was introduced to replace the T600A. It also had a nearly identical design to the T600A, with a few adjustments made to fulfill the then-current revised conventional-cab specifications. The sleeping units of the T600B used the innovative Aerocab sleeper concept, which combined the cab and sleeper into one unit rather than two.

Despite the minor updates, the T600B won the National Award for the Advancement of Motor Vehicle Research and Development from the US Department of Transportation in 1995.

2007 Kenworth T660

The Kenworth T660 formally replaced the T600 in 2007. While it retained most features of the T600, it sported upgrades that further pushed the line’s aerodynamics and fuel efficiency.

The T660 was manufactured with an updated hood and fenders to enhance its aerodynamics. These fenders are paired with composite headlamps and two-panel grilles similar to the T2000. The front axles were updated to 12,000-14,600lb, and the rear axles to 23,000-46,000lb, ensuring maximum performance and efficiency regardless of a full payload.


Fuel-efficient Kenworth T660

Most importantly, the T660 used a new diesel-powered engine from PACCAR to meet new emission requirements, boosting the model’s fuel efficiency. The reported average fuel use of the T660 is 6.5 mpg at idle and 6.6 mpg while running, which is truly impressive for a Class 8 conventional-cab truck.

Aside from these changes, the T660 sleeper units retained the Aerocab sleeper format of the T600. The sleeper sizes ranged from 38-86 inches, with high-roof Aerodyne on the longest units and low-profile FlatTop on the shorter ones.

2013 Kenworth T680

Kenworth released the T680 to fulfill the EPA13 emission criteria, thereby replacing the T660. The truck is also easier to handle and maintain due to its TruckTech+ features and digital mirrors. Because of this, the model is known as the “Next Generation.”


2013 Kenworth T680

Thankfully, Kenworth carried on the T600’s tradition of fuel efficiency because the T680’s EPA21 PACCAR MX13 engine boosted powertrain efficiency.

Proving the Efficiency of Kenworth T660

Because of the T660 Regional Transporter model’s capacity to save fuel, Kenworth sold 1,600 of them in 2011-2012. Business owners claim that a single T660 unit can provide better aerodynamic advantages, lighting features, and fuel efficiency compared to more expensive regional haulers. 

The Chippewa Sand Transport company put the T600 units through a few tests to demonstrate the T660’s potential for efficiency. 

The most fuel-efficient model configuration was the T660 Regional Hauler with a 12.9-liter PACCAR MX engine. It had an anticipated fuel economy of 6 mpg for a 23-mile trip at an average speed of 40 mph. Sand was used to fill the unit.


Kenworth T660 Regional Haulers

By producing 6.5 mpg at idle and 6.6 mpg while moving, the T660 unit outperformed their expectations at the end of the test. It’s also important to note that the tested device had yet to be broken in, so when it operates at its best, it should achieve 7 mpg. 

A business using T660 in its hauling operations can save up to $325,000 a year in fuel, given that the expected diesel price is $4.2 per gallon. That amounts to more than $300,000 that can be set aside for business growth. 

The company put its T660 regional haulers through additional testing, using them to transport lime, cement, fly ash, and other products over a 500-mile radius. The units maintained the same fuel efficiency.

According to Chippewa’s research, the Kenworth T660 is undoubtedly one of the most effective and profitable conventional-cab trucks ever produced.

Unleash the Full Potential of Your Kenworth T660

Truck owners are well aware of the enormous impact the HVAC system can have on their day to day comfort. And the same is true for the Kenworth T660. Despite its well-proven design and fuel efficiency, an inadequate HVAC system can prevent it from operating to its full potential. 

We recommend seeking a HVAC box with a stainless steel box body and an upgraded blower motor to get the most out of your T660. The new HVAC unit will operate at peak efficiency thanks to the 15% increase in CFM above OEM.


Premium HVAC for Kenworth T660

This HVAC upgrade will help ensure owners and drivers stay comfortable while enjoying all the great features of the T660. There’s no denying that Kenworth really delivered on its promise of excellent fuel economy with the T660. With the right configurations and proper maintenance, the T660 can generate a good ROI for all business owners.

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