School Bus Fleet
MenuMENU
SearchSEARCH

ROUSH CleanTech Propane Autogas Engines Now Standard with Ultra-Low NOx Emissions

Explore the latest advancements in propane autogas engines with standard ultra-low NOx emissions. Discover how these engines exceed regulations, promote environmental sustainability, and contribute to improved air quality.

ROUSH CleanTech Propane Autogas Engines Now Standard with Ultra-Low NOx Emissions

The Roush CleanTech propane engines are used in Blue Bird school buses and other commercial vehicles.

Image: Canva/PERC

2 min to read


ROUSH CleanTech has achieved California Air Resources Board certification for its 2023 model year propane engines, which emit ultra-low nitrogen oxide (NOx) emissions at 0.02 grams per brake horsepower-hour.

Propane Autogas Environmental Benefits and Regulatory Compliance

Previously an optional feature, the low NOx emissions package is now standard across all ROUSH CleanTech propane engines. These engines exceed 2023 regulations by emitting 90% less NOx emissions and are 60% cleaner than California's 2024 low-NOx standard, while maintaining performance and efficiency.

Ad Loading...

Nitrogen oxides, recognized as a significant contributor to environmental issues like acid rain and smog, can pose health risks, particularly for children, including asthma and respiratory problems. On the other hand, operating vehicles with ultra-low emission engines significantly improves regional air quality and mitigates various health impacts, according to the EPA.

“Customers can rest easy knowing that ROUSH CleanTech propane engines provide ultra-low NOx emissions with no added cost today. And, we are well on our way to meeting California and EPA’s emissions standards for 2027 and beyond,” said Todd Mouw, executive vice president at ROUSH CleanTech.

Incentives and Adoption Opportunities for Fleets

Fleet operators purchasing the 2023 models can take advantage of various state and federal incentives, such as the Clean School Bus Program under the Infrastructure Investment and Jobs Act, as well as the Volkswagen Environmental Mitigation Trust settlement.

ROUSH CleanTech, an alternative fuel technology company, introduced low NOx engines in 2018 and became the first manufacturer to receive CARB's ultra-low 0.02 grams per brake horsepower-hour certification for Blue Bird school buses and commercial vehicles in 2021. Mouw emphasized that the company achieved this certification ahead of regulations.

ROUSH CleanTech's latest technology and the availability of renewable propane highlight how the fuel has evolved from being merely a "bridge" to a long-term solution for transportation energy. Adopting renewable propane allows fleets to operate with comparable power and reliability to conventional propane. Additionally, renewable propane has an ultra-low carbon intensity and is carbon neutral when combusted.

Ad Loading...

Over 37,000 advanced clean vehicles equipped with ROUSH CleanTech's engines are currently on the road, including 18,500 school buses in 1,000 U.S. school districts. Mouw reaffirmed ROUSH CleanTech's commitment to offering environmentally friendly vehicle solutions that utilize domestically produced, cost-effective propane autogas engines.

More Alternative Fuels

School Bus Fleet graphic reading “Alt-Fuel Moves: Bidirectional Charging & Propane” alongside an electric school bus and charging station.
Alternative Fuels•by Elora Haynes•October 5, 2026

Alt-Fuel Moves: Electric Bus Rollouts, Bidirectional Charging & Propane Growth

See which fleets are adding electric and propane school buses as districts and operators invest in charging infrastructure, bidirectional technology, and alternative-fuel expansion.

Read More →
School Bus Fleet graphic reading “When Fuel Prices Change the Math: What rising diesel costs mean for fleet planning,” illustrated with a fuel pump and oil barrels.
Alternative Fuels•by Steve Mitchell•October 4, 2026

Nobody Told Diesel Prices They Were Supposed to Come Down

With diesel prices surging, school bus fleets have new reason to stress-test fuel costs, consider diversification, and calculate what each route really costs to operate.

Read More →
Yellow full-size school bus traveling along a tree-lined road beneath the words “Gas is Back!” in a School Bus Fleet graphic.
Alternative Fuels•Cover Story•by Amanda Huggett•October 2, 2026

Why Gasoline School Buses Are Making a Comeback

Gasoline is gaining ground in full-size school buses. See how today’s options stack up against diesel on cost, maintenance, emissions, performance, and more.

Read More →
Ad Loading...
EPA DERA funding graphic featuring a yellow school bus beneath a blue sky with the EPA logo and the words “DERA Funding Returns!”
Alternative Fuels•by Amanda Huggett•September 25, 2026

EPA Opens $180M DERA Funding Round for Diesel Upgrades

The 2026 Diesel Emissions Reduction Act program seeks applications from eligible organizations to accelerate the retirement of legacy diesel vehicles.

Read More →
A yellow RIDE Type D electric school bus is parked along a tree-lined street outside a school.
Alternative Fuels•by Elora Haynes•September 25, 2026

The Secret Life of an Electric School Bus Battery

Batteries change throughout years of daily routes, but degradation doesn’t necessarily mean the end. Here’s what operators should know about performance, safety, and second life.

Read More →
Catalyst Mobility: Building Clean Transportation Together
Management•by Alex Roman•September 14, 2026

CALSTART and Forth Combine to Form Catalyst Mobility

The new name represents a renewed vision for the nonprofit focused on advancing clean, equitable, and affordable transportation solutions that move people and goods.

Read More →
Ad Loading...
An orange and yellow graphic with a black and white image of a propane deployment event with text reading "Charging Hubs & Real World EV Testing."
Alternative Fuels•by Elora Haynes•September 3, 2026

Alt-Fuel Moves: New Buses, Charging Hubs & Real-World EV Testing

Propane and electric school bus deployments continue to grow as districts add new vehicles, expand charging infrastructure, and gather more real-world operating data.

Read More →
Electric school buses parked in a parking lot.
Alternative Fuels•by Elora Haynes•August 24, 2026

Fewer Electric School Bus Models Reshape the U.S. Market

WRI’s latest buyer’s guide points to a consolidating electric school bus market, but fewer options may reflect a maturing industry rather than fewer meaningful choices for school bus operators.

Read More →
A yellow school bus with its red stop arm extended is stopped to load or unload students as a blurred child crosses in the foreground, illustrating the importance of motorists stopping for school buses and protecting students in the loading zone.
Alternative Fuels•August 12, 2026

The Fuel Budget You Can Actually Predict: How Propane Autogas Keeps Money in the Classroom

Learn how propane autogas helps school districts manage fuel costs with predictable pricing, lower maintenance, and reduced emissions from former transportation director Joel Stutheit.

Read More →
Ad Loading...
Graphic promoting Hendrickson's new ELECTRAAX electric axle system, featuring a red electric drive axle assembly with high-voltage orange cables connected to a control module. The Hendrickson logo and tagline, "The World Rides On Us," appear above the product against an orange gradient background, with a "New Product" label in the upper left and the School Bus Fleet logo in the lower right.
Alternative Fuels•August 12, 2026

Hendrickson, Driventic Introduce New Electric Powertrain for School Buses

ELECTRAAX, the electrified, lightweight drive axle offers integrated ePowertrain efficiency and modular flexibility for Class 6–7 school bus use.

Read More →