The Express/Savana 4500’s capability is supported by a new, stronger chassis that enables a 14,200-pound (6,441 kg) GVW with lower mass – giving it a best-in-class payload rating of 9,100 pounds (4,127 kg).*

“The new 4500 chassis brings real choice to Class 4 customers, with great capability, exceptional engineering and numerous best-in-class attributes,” said John Gaydash, director of marketing, GM Fleet and Commercial Operations. “And we are the only OEM to offer an emissions-compliant V-8 diesel in this GVW category.”

The new Express/Savana 4500 is offered with a gas V-8 and GM’s popular 6.6L Duramax turbo-diesel V-8, offering better fuel economy over larger engines. With the new, strong frame and robust powertrains, the Express and Savana 4500 offers up to a 20,000-pound (9,072 kg) GCWR, for exceptional towing and RV capability.

Each model comes with GM’s five-year, 100,000-mile limited powertrain warranty.

Unique frame enhancements, chassis design details and drivetrain features deliver great flexibility in a single platform, while the 4500’s more robust body structure is designed to handle the extreme duty cycle encountered by many cutaway vehicles. Highlights include:

• Reinforced frame assembly
• New rear axle with reinforced housing, gears and axle tubes
• Upgraded rear spring hanger bolt attachments and leaf spring shackle assembly
• High-capacity rear spring assembly
• Upgraded front ball joint material
• Revised front and rear shock tuning
• Rear stabilizer bar
• Enhanced parking brake system with thicker rear brake rotors for improved heat dissipation
• Enhanced driveshaft hanger
• Higher-capacity radiator
• Standard transmission cooler

The frame enhancements are numerous and strengthen an already sturdy chassis, but the chassis was carefully engineered to minimize mass – in other words, the frame reinforcements and other provisions for upfits were targeted to provide the most benefit with minimal impact on capability.

Brackets added to the upper and lower portions of the frame’s side rail bulkheads provide reinforcing strength, as do kick-up reinforcements near the rear axle area. The body-in-white structure is also strengthened, with 10-percent-thicker steel used in key areas, as well as additional spot welds and structural adhesive. These enhancements enable the 4500’s capability while delivering a solid feel.

With approximately 2,500 pounds in GVCW gained with the 4500 chassis, it makes an ideal platform for RVs and offers increased seating for school bus applications.

“The engineering of the new Express and Savana 4500 allow them to do more with less,” said Gaydash. “The competition offers a 14,500 GVW, but due to the 4500’s lower mass we’ve got a higher payload – 9,100 pounds versus their 8,900 pounds.”

Powertrain and fuel system details

The 4500 chassis is available with a Vortec 6.0L gasoline V-8 or the Duramax 6.6L V-8 turbo-diesel. The emissions-compliant Duramax 6.6L was introduced as an interim change during the 2007 model year, and features a host of enhancements that enable it to deliver reduced emissions using cleaner, federally mandated Ultra Low Sulfur fuel. It is rated at a best-in-class 250 horsepower (185 kW) and best-in-class 460 lb.-ft. of torque (636 Nm).

A new, electronic variable cooling fan is used with the Duramax engine. It delivers improved cooling control and quieter operation than a conventional mechanical (engine-driven) fan.

The Vortec 6.0L gas engine features variable valve timing for enhanced performance and optimized fuel economy; it is rated at a best-in-class 323 horsepower (173 kW). The Vortec 6.0L is based on GM’s Gen IV small-block V-8 engine family that features strength-enhancing features such as a deep-skirt cylinder block and cross-bolted six-bolt main bearing caps.

A Hydra-Matic HD 4L85E electronically controlled four-speed automatic transmission backs both available engines. It was designed for the heavy-duty use of commercial cutaway vans and features a brazed torque converter turbine, induction-hardened turbine shaft, five-pinion reaction and output gear carriers and an improved overrun roller clutch.

The 2009 4500 includes GM’s exclusive Oil Life System that determines when to change oil and filter based on engine operating conditions. Use of the GMOLS will often double or even triple the oil change interval for a typical vehicle when compared to the 3,000-mile oil change. Overall operating costs for customers will be lower, because they only have to change the oil when indicated.

All 4500 chassis (except school bus applications) with the 14,200-pound GVWR and Duramax diesel engine receive a new, 57-gallon rear-mounted fuel tank that was designed with input from upfitters. The tank is mounted lower on the chassis, providing a flat mounting position for ambulance bodies and more.

The 57-gallon tank’s fuel sender and all the fuel lines are upgraded to meet B5 bio-diesel performance requirements.

GM’s upfitter and SVM relationships

General Motors consulted with special vehicle manufacturers (SVMs) and upfitters during the 4500 chassis’ development, creating a single Class 4 chassis that serves a variety of needs, including school bus, ambulance and shuttle bus vocations. This means an upfitter or SVM can develop and get its vehicle package to market more quickly, as there is far less customization required.

GM’s relationship with upfitters and SVMs serves as a conduit between GM and the end user, giving the customer a better product that has the features, specifications and capability they demand. It also provides customers with a streamlined ordering process, lower shipping costs and shorter lead times.

*Pending certification.

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4500 SPECS

Overview

Engines

Transmissions

Chassis/Suspension

Wheels/Tires

Dimensions

Interior

Capacities

*Cooling capacity higher with fuel-operated heater

Note: Information shown is current at time of publication.