Back-of-Cab CNG Fuel System

Medium- and Heavy-Duty Trucks

Available in 123, 160, and 180 DGE, Q-Cab integrates three high-capacity, extremely lightweight tanks into one elegant, aerodynamically invisible system. Grid-friendly and easy to install, Q-Cab can be combined with our dual Q-Rail system for extended range. Subjected to rigorous vibration testing, Q-Cab is proven extremely durable and comes with our 2-year 200,000-mile warranty. It has industry leading features like a fill door with lockout switch, hook and hang assembly, easy maintenance, compact design and right-hand fill (option).


  • Available in 123, 160, and 180 DGE
  • Extremely lightweight design
  • Robust with increased durability
  • Easy to install with hook & hang mounting mechanism
  • Grid-friendly design with variable width and mounting hold options
  • Filter and service components are located above the frame rails
  • A safety switch detects if the door is left open, prohibiting the vehicle from starting
  • Equipped with three Q-LiteTM tanks, the lightest CNG tank in the industry
  • Increased flexibility to add frame modules
  • Supports up to 273 DGE when combined with dual 46.5 DGE Q-Rail CNG fuel modules
  • Automotive grade OEM white paint standard. Custom paint colors available
  • 2-year 200,000 mile warranty
Back-of-Cab CNG system
cng system
cng system front view
Back-of-Cab Fuel Gauge

How to buy

Call sales at (949) 930-3400

Features and Benefits

Quantum’s culture of innovation continues to improve the efficiency of alternative vehicle technology. We make vehicles go farther; we increase storage capacity and reduce weight; we improve service and customer experience; we lower your overall cost of investment. Because we manufacture our own components, as well as design, engineer and develop our own fuel and control systems, we provide the best value in the industry.

Lightest Systems & Tanks
Quantum Q-Lite™ tanks, Q-Rail and Q-Cab fuel system modules are the industries lightest.

Lightest Systems & Tanks

Highest Capacity Tanks
Optimized composite shell enables us to store more fuel.

Highest Capacity Tanks

Most Durable Systems
Our Q-Cab fuel system module completed 1 million miles of durability testing.

Most Durable Systems

Highest Quality Products
ISO/TS 16949 Automotive Quality Management System & ISO/TS 14001 Environmental Management Standards Certified.

Highest Quality Products


Product Description Q-Cab 41 Q-Cab 123 Q-Cab 160 Q-Cab 180
Part Number 116943 116074 117345 117155
Diesel Gallon Equiv. (IA) DGE 41 123 160 180
Gasoline Gallon Equiv. (IA) GGE 47 140 184 206
Module Length Inches 86 86 89 89
Module Height Inches 33 84 104 104
Module Depth Inches 33 33 37 37
Q-Lite Tank Installed Units 1x 25×80 3x 25×80 1x 25x 80 + 2x 30.5×83 3x 30.5×83
Fill Location Left Left Fill Left Fill Left Fill
Module Fill Panel No Yes Yes Yes
Regulator Included No Yes Yes Yes
High Flow Fill System Yes Yes Yes Yes
Module Weight – empty lbs 580 1,759 2,180 2,314
Tank Capacity (Water Volume) Gallons 140.6 421.8 554.8 621.3
Range @ 6 MPG Miles 210 630 822 918
Length. Maximum @ 125% SP Inches 80.5 80.5 80.5/83.5 83.5
Service Pressure @ 70 °F psi 3,600 3,600 3,600 3,600
Tank + Gas Weight @ 3600 psi lbs 445 1,335 1,841 2,981
CNG Mass @ 3600 psi lbs 224.7 674.1 886.9 993.3
CNG Volume @ 3600 psi SCF 5,030 15,090 19,854 22,236
Usable Gas Mass @ 290-3600 psi lbs 195.2 585.6 770.4 862.8
* Other smaller fuel storage systems with 21″ tank sizes are available upon request.
* All dimensions are estimates.

Media Gallery

Quantum Clean Fuel Systems Overview and Virtual Pipeline

Q-LiteTM – The Right Tanks for CNG Trucks

Why Quantum Natural Gas Fuel Systems

What Our Customers Say?

We chose Quantum because they really listened to our needs and their system gives us the best value in regards to weight and price.
Juan Corcino
Director of Fleet/OPS, ManhattanBeer Distributors

The Quantum Warranty

We stand behind every product we make. Our Fuel System are backed by a two-year/ 200,000-mile warranty. With no deductible or service charges, it’s one of the most comprehensive warranties in the industry, plus it’s fully transferable during the warranty period. Our more than 20 years in the clean fuel vehicle business prove that we’ll be here to service your needs for many years to come.

Quantum Service Network

We’re constantly expanding our service network to help our customers more efficiently. If you’re interested in becoming an authorized Quantum Service Center, contact us.

Service Centers

Our customer service is second to none. We know the importance of keeping your trucks on the road; our Service Team will assist you in doing just that. With 20+ years in the CNG industry our service team has the knowledge and experience to help your technicians diagnose a problem and get parts for a quick repair turn around. Partnering with service centers, we leverage a broad range of capabilities to efficiently maintain and repair your vehicle and increase your uptime.

For a service center near you, call 1-800-816-8691.


Quantum’s Type IV tanks are validated by the stringent requirements of NGV2, and our systems comply with or exceed all applicable industry standards. But Quantum goes beyond industry requirements to ensure safety and reliability—and beyond any other fuel system provider—with the most rigorous thermal, shock, vibration, impact, and corrosion, testing in the industry.

Why Natural Gas?