When introduced into the Class 8 market in 2006 at the Mid America Trucking Show, Kenworth tagged its T660 as the “latest evolution” of the aerodynamic and fuel efficient side of its product line. Mike Dozier, Kenworth’s chief engineer at the time, noted that the T660 grille was 5% larger to accommodate the increased airflow and cooling performance required by then-new 2007 emission-reducing engines. “Yet, we were able to actually achieve a positive increase in aerodynamics and fuel economy,” he said. “We used computational fluid dynamics (CFD) analysis extensively to fine-tune the aerodynamic performance of the whole vehicle.” (Photo by Kenworth)
Other key features of the T660 back in the day included: Halogen projector low beams that provided 40% more light down the road than a sealed beam lamp and last three times longer; enhanced multiplexed electrical instrumentation system; optional GPS navigation system; and a new driver’s dashboard display with real-time fuel economy, ignition timer, on-board diagnostics, gear display, vehicle system configuration reporting; plus proprietary seats that featured armrests that can be folded away behind the seat, giving occupants an additional four inches of sleeper access between driver and passenger seats.
I had the good fortune to get some up close and personnel time with the T660 over the years. One of the best included a 2007 ride and drive out of the Paccar Technical Center in Mt. Vernon, Washington, as well as a detailed walk-around down in Orlando, Florida, (seen here in this picture) during the 2009 Technology & Maintenance Council (TMC) meeting. (Photo by Sean Kilcarr/Fleet Owner)
Kevin Tobin, then serving as the general sales and service manager-East region for Kenworth back in 2009 (he's since been kicked upstairs to general sales and service manager) told me at the time the T660 was all about making small fuel efficiency improvements add up to big ones. “It’s all about gaining a tenth of a gallon improvement in fuel economy over here, another tenth over there, and suddenly you’re saving half a mile or more per gallon – and that really adds up over the ownership period for the truck,” he said. (Photo by Sean Kilcarr/Fleet Owner)
Back in the day, Tobin showed me how Kenworth’s engineers went back and developed a bigger grab handle for the engine hood – one a driver can fit their hand in while wearing a glove – that not only has a drain at the bottom so water or snow doesn’t accumulate but one that’s also integrated into the aerodynamic styling of the hood so it doesn’t create even the tiniest amount of drag. A special automatic locking mechanism also makes sure that once the hood is open, a gust of sudden wind doesn’t knock it closed. (Photo by Sean Kilcarr/Fleet Owner)
The “Clean Power” package Kenworth introduced with its T660 – a factory-installed, battery-powered no-idle system that could enhance fuel economy by as much as 8% – fit onto the truck so discretely behind the cab and under the driver’s bunk that you wouldn’t even know it was there. (Photo by Sean Kilcarr/Fleet Owner)
The last Kenworth T660s are going to come standard with the PACCAR MX-13 engine, rated at 455-hp and 1,650 lb.-ft. of torque, and will be available as a day cab or with 38-in., 62-in., 72-in., or 86-in. AeroCab sleepers. (Photo courtesy of Kenworth)
Kenworth also donated a few T660s to some charitable causes during its 10-year run – one of them to the Swedish Cancer Institute, which turned the vehicle into a mobile mammography facility to reach women who normally have limited access to health care.
Kenworth’s Jason Skoog noted that Kenworth continued to offer the T660 even after introducing its nominal replacement, the T680, four years ago. Yet since 2012, more and more T660 customers switched to the T680, meaning the time to retire the T660 has arrived.