Speed Governors in Trucking: How They Work & What Drivers Need to Know
Speed governors — also called speed limiters or electronic speed limiters — cap the maximum speed a truck can travel. Whether you are a company driver dealing with a governed truck or an owner-operator weighing the pros and cons, understanding how governors work, why carriers use them, and the ongoing regulatory debate helps you make informed career decisions.
62-68 MPH
Typical Governor Setting
1.0 MPG
Fuel Savings (65 vs 75 MPH)
525 ft
Stopping Distance at 65 MPH
$8K-$12K
Annual Fuel Savings Per Truck
O Trucking Editorial Team
Trucking Industry Experts
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5+ years helping carriers optimize safety, compliance, and operational efficiency
This article was written by the O Trucking editorial team with 9+ years of combined trucking industry experience. Learn more about us.
O TruckingSpeed Governors in Trucking: How They Work & What Drivers Need to Know
What Is a Speed Governor?
A speed governor (also called a speed limiter, electronic speed limiter, or road speed limiter) is an electronic system that restricts the maximum speed of a commercial motor vehicle. The governor works through the truck's Engine Control Module (ECM), which controls the fuel delivery to the engine. When the truck reaches the programmed maximum speed, the ECM reduces fuel flow to prevent further acceleration, regardless of how far the driver presses the accelerator pedal.
Speed governors are not a new concept. Mechanical governors have been used on engines since the steam engine era. In modern trucking, electronic governors became standard in the late 1990s and early 2000s when engine manufacturers transitioned to fully electronic engine management systems. Today, virtually every Class 8 truck manufactured since 2000 has the hardware capability for electronic speed limiting built into its ECM.
The key distinction is between the capability and the activation. While almost all modern trucks can be governed, whether the speed limiter is actually enabled and at what speed it is set depends on the carrier's policy. Most large fleet carriers activate the governor; many owner-operators running under their own authority choose not to.
How Speed Governors Work
The speed governor operates through a straightforward electronic process:
1. Speed Sensing
The vehicle speed sensor (VSS) on the transmission or wheel hub continuously sends speed data to the ECM. This sensor measures driveshaft or wheel rotation speed and converts it to miles per hour. The ECM reads this data in real time, typically sampling dozens of times per second.
2. Speed Comparison
The ECM compares the current vehicle speed to the programmed maximum speed stored in its software. This maximum speed parameter is set by authorized personnel using the engine manufacturer's diagnostic software — tools like Cummins INSITE, Detroit Diesel DDDL, or Navistar Diamond Logic.
3. Fuel Reduction
When vehicle speed reaches or exceeds the programmed limit, the ECM progressively reduces fuel injection to the engine. The truck does not brake — it simply stops accelerating. On a downhill grade, the truck can exceed the governed speed because gravity, not engine power, is providing the acceleration. This is why cruise control and engine brakes (jake brakes) are important complements to speed governors.
4. Password Protection
The governor setting is protected by a multi-level password system in the ECM software. Fleet managers and authorized technicians have different access levels. Changing the governed speed requires the fleet-level password, which is typically controlled by the carrier's safety department. Individual drivers do not have access to change these settings.
Governors Don't Work on Downhills
Carrier Speed Policies
Each carrier sets its own governed speed based on a balance of safety, fuel costs, driver satisfaction, and insurance considerations. Here is how major carriers typically set their governors:
| Carrier | Base Governor Speed | Performance Unlock | Notes |
|---|---|---|---|
| Werner Enterprises | 65 MPH | Up to 68 MPH | Safety record-based unlock |
| Schneider National | 63 MPH | Up to 65 MPH | Strong fuel bonus program offsets lower speed |
| Swift / Knight-Swift | 65 MPH | Up to 67 MPH | Tiered system based on tenure and safety score |
| J.B. Hunt | 65 MPH | N/A | Fixed governor speed for all company trucks |
| CRST International | 62 MPH | Up to 65 MPH | One of the lowest base settings among megas |
| Heartland Express | 64 MPH | Up to 67 MPH | Performance-based unlock available |
Ask About Governor Speed Before You Sign
FMCSA Regulations & the Federal Speed Limiter Debate
The federal government has been debating a mandatory speed limiter rule for commercial trucks for over a decade. Here is the timeline and current status:
2006 — The American Trucking Associations (ATA) petitioned NHTSA to require speed limiters on all trucks over 26,000 lbs GVWR, suggesting a 68 MPH limit.
2016 — FMCSA and NHTSA jointly published a Notice of Proposed Rulemaking (NPRM) requiring speed limiters on all new trucks manufactured after the rule's effective date. The proposal asked for public comment on settings of 60, 65, or 68 MPH.
2017-2020 — The rule was repeatedly delayed and eventually removed from the regulatory agenda under the Trump administration, which prioritized reducing regulatory burden on the trucking industry.
2022 — FMCSA issued a Supplemental Notice of Proposed Rulemaking (SNPRM), reviving the speed limiter mandate and expanding it to potentially cover existing trucks, not just new ones. The proposal included possible maximum speeds of 60, 65, or 68 MPH.
2024-2025 — The rule remains under review. No final rule has been issued. The trucking industry remains divided, with the ATA supporting a 65 MPH mandate and OOIDA opposing any mandatory limiter requirement.
State Speed Laws Still Apply
Pros of Speed Governors
The arguments in favor of speed governors are primarily centered on safety, fuel economy, and operational costs:
Reduced crash severity — A fully loaded 80,000-lb truck at 65 MPH has roughly 44% less kinetic energy than the same truck at 75 MPH. When crashes do occur at lower speeds, the forces involved are significantly less, reducing injury severity and fatality risk. FMCSA research estimates that a 65 MPH limiter mandate could prevent 63 to 498 fatalities annually.
Significant fuel savings — Fuel consumption increases exponentially above 55 MPH due to aerodynamic drag. Governing a truck at 65 MPH instead of 75 MPH saves approximately 1.0 MPG, translating to $8,000-$12,000 per truck per year in fuel costs. For a 5,000-truck fleet, that is $40-$60 million annually.
Lower insurance premiums — Insurance companies offer discounts to carriers that govern their trucks. The reduction varies, but carriers with governors set at 65 MPH or below typically see 3-8% lower liability insurance premiums compared to ungoverned fleets.
Reduced tire and brake wear — Higher speeds generate more heat in tires and brakes, accelerating wear. Trucks governed at lower speeds see measurably longer tire life (5-10% improvement) and brake component life, reducing maintenance costs over the vehicle's lifespan.
Improved CSA scores — Fewer speeding violations mean better Unsafe Driving BASIC percentiles. Carriers with governed trucks have measurably lower rates of speeding citations during roadside inspections, which directly improves their CSA safety profile.
Cons & Driver Concerns
The arguments against speed governors — particularly mandatory ones — are primarily raised by drivers and owner-operator advocacy groups:
Dangerous speed differentials — When trucks are governed at 65 MPH but passenger traffic flows at 75-80 MPH, the 10-15 MPH speed differential creates more lane-change conflicts, more passing attempts by cars, and increased risk of rear-end collisions. Studies from Virginia Tech Transportation Institute found that speed differentials — not absolute speed — are a significant contributing factor in multi-vehicle crashes.
Reduced ability to avoid hazards — In certain situations, briefly accelerating is the safest response (merging onto a highway with fast-moving traffic, passing another vehicle on a two-lane road, or clearing an intersection). A governor that caps speed at 65 MPH eliminates this option for drivers who are already at or near the governed speed.
"Elephant races" — When two governed trucks set at slightly different speeds (e.g., 63 and 65 MPH) try to pass each other, the passing maneuver can take a mile or more. This blocks the passing lane for extended periods, frustrating other drivers and creating traffic congestion and unsafe conditions.
Reduced earning potential — Drivers paid by the mile earn less when governed at lower speeds because they cover fewer miles per driving hour. The difference between 62 MPH and 68 MPH can mean 15,000+ fewer miles per year, costing a driver $8,000 or more annually in lost mileage pay.
Driver frustration and fatigue — Many drivers report that being governed creates mental fatigue from constantly managing speed, especially on highways with speed limits above their governor setting. The frustration of being unable to pass slower vehicles or keep pace with traffic is a commonly cited quality-of-life complaint.
Owner-Operators & Speed Governors
For owner-operators running under their own MC authority, the decision to use a speed governor is currently voluntary. Here are the key considerations:
Leased to a Carrier
If you are an owner-operator leased to a carrier, the carrier typically controls the governor setting. Even though you own the truck, the carrier's insurance policy and safety program cover you while operating under their authority. Most carriers will require their ECM technicians to set the governor before you begin operating. Check the lease agreement carefully — changing the governor setting without authorization is usually a lease violation.
Running Under Own Authority
Owner-operators with their own MC authority and DOT number have full control over their truck's governor setting. Many choose not to govern their trucks, arguing that it limits flexibility and earning potential. However, some owner-operators voluntarily set a governor at 70-72 MPH to save fuel while still maintaining the ability to keep up with traffic. Some insurance companies also offer discounted rates for owner-operators who can demonstrate governor use.
The Fuel Economy Math
Even without a mandatory requirement, the fuel savings alone make a compelling business case. An owner-operator running 120,000 miles per year at 6.5 MPG (governed at 65) vs. 5.5 MPG (ungoverned at 75) saves roughly 3,600 gallons annually. At $3.75/gallon, that is $13,500 in fuel savings — money that goes straight to your bottom line. Many owner-operators find that a moderate governor (68-70 MPH) balances fuel savings with schedule flexibility.
Consider a Self-Imposed Governor
The Bottom Line
Speed governors are a fact of life for the majority of company drivers at major carriers. The settings typically range from 62 to 68 MPH, with performance unlock programs offering a few extra MPH for drivers with clean records. The federal mandate debate continues, but the practical reality is that most trucks on the road are already governed because carriers see clear benefits in fuel savings, insurance costs, and safety performance.
For drivers evaluating carriers, the governed speed is an important factor in your earning potential and daily driving experience. A 3 MPH difference in governor setting might sound small, but over a year it can mean 7,500+ miles and $4,000+ in mileage pay. Always ask about the governor speed and performance unlock criteria during the interview process.
For owner-operators, the decision is a business calculation. The fuel savings from even a moderate governor at 68-70 MPH are substantial, and voluntary use can qualify you for insurance discounts. Regardless of your governor stance, maintaining safe speeds and proper following distances is always the most important speed management practice on the road.
Speed Governors FAQ
Common questions about speed governors and speed limiters in trucking
What speed are most trucking company governors set to?
Most major carriers set their speed governors between 62 and 68 MPH. The exact setting varies by carrier: Werner Enterprises typically sets governors at 65 MPH, Schneider National at 63 MPH, Swift Transportation at 65 MPH, and J.B. Hunt at 65 MPH. Some carriers offer a performance bonus that unlocks slightly higher governor settings (often 2-3 MPH more) for drivers who maintain clean safety records, good fuel economy, and high on-time delivery percentages. Owner-operators running under their own authority generally do not use speed governors unless required by a leased carrier.
Can a truck driver adjust or disable the speed governor?
No. Speed governors are programmed through the truck's ECM (Engine Control Module) and require specialized diagnostic software to change. Only authorized fleet maintenance personnel or dealership technicians can modify the governor setting. Tampering with the ECM to bypass the speed governor is a serious offense that can result in immediate termination, voiding of the truck's warranty, and potential liability issues if an accident occurs. Some aftermarket tuners claim to remove speed limiters, but using them on a company truck or a leased vehicle is a violation of your employment or lease agreement.
Is there a federal law requiring speed governors on trucks?
As of 2025, there is no federal law mandating speed governors on commercial trucks. However, the FMCSA and NHTSA jointly proposed a rule in 2016 that would require speed limiters on all trucks with a gross vehicle weight rating above 26,000 pounds. The proposal suggested settings between 60 and 68 MPH. The rulemaking process stalled and was withdrawn from the regulatory agenda multiple times, though it has been reintroduced periodically. Several trucking industry groups including the ATA (American Trucking Associations) support a national speed limiter mandate at 65 MPH, while the OOIDA (Owner-Operator Independent Drivers Association) strongly opposes mandatory limiters.
Do speed governors improve fuel economy?
Yes, significantly. The relationship between speed and fuel consumption is not linear — it is exponential above about 55 MPH. According to the U.S. Department of Energy, every 1 MPH increase above 50 MPH costs roughly 0.1 MPG in fuel economy. A truck governed at 65 MPH instead of 75 MPH can save approximately 1.0 MPG, which translates to roughly $8,000 to $12,000 per year in fuel savings based on 120,000 miles annually and diesel prices around $3.50 to $4.00 per gallon. This fuel savings is the primary reason most carriers adopted speed governors long before any regulatory push.
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