Speed limiter impact calculator: what a governed truck gains and loses
Enter your weekly driving hours, how much is highway cruise, today's cruise speed and the governed speed, plus rate and fuel economy. The speed limiter impact calculator shows miles lost, revenue lost and fuel saved per week.
Speed limiter impact calculator
EXAMPLE VALUES, REPLACE WITH YOURSPER TRUCK, PER WEEK
195
miles lost per week
-$77
net per week (fuel saved minus revenue lost)
- Revenue lost
- -$439
- Fuel saved
- $361
- Extra hours to drive the same miles
- 3.0 h
195 miles a week lost to governed speed. Planning loads around it matters more than the top speed.
By Edwin Horton · Updated
How the speed limiter calculator works
A governed truck only slows down on open highway. Traffic, ramps, cities and docks run at the same speed either way. The calculator separates the two.
- Miles today = hours × highway share × cruise speed + hours × the rest × average slow speed
- Miles governed = the same, with the highway part at the governed speed
- Miles lost = miles today − miles governed
- Revenue lost = miles lost × rate per mile
- Fuel saved = fuel for today's miles at today's mpg − fuel for the governed miles at your governed mpg
- Extra hours = the driving time needed to make up the miles at the governed speed
EXAMPLE A truck drives 52 hours a week, 75% at a 70 mph cruise and the rest averaging 38 mph. Governed at 65 mph, it loses 195 miles a week. At $2.25 a mile that's about $439 of revenue. If fuel economy improves from 6.4 to 6.8 mpg at the lower speed, with diesel at $6.20, fuel drops by about $361 a week, so the net change is about -$78. Your mpg numbers decide most of this answer.
The rules
There's no federal speed limiter requirement for heavy trucks; the proposal was withdrawn in July 2025 Federal speed limiter proposalWithdrawn July 24, 2025; no federal speed limiter mandateFMCSA and NHTSA withdrew the proposed rule that would have required speed limiting devices on heavy trucks (Federal Register 2025-13928). Speed limiters remain a fleet, insurer or customer choice, not a federal requirement.Federal Register 2025-13928, 2025Checked Oct 2026. Posted speed limits still apply, and many states set lower truck limits than for cars. Governing a truck is a fleet choice.
Fuel saved against miles lost
Net close to zero: fuel savings roughly cover the lost miles. Other effects then decide it: brake and tire wear, insurance terms, driver preference and safety.
Big revenue loss: the truck depends on long highway runs to make its week. Delivery windows may also get harder to meet. Plan pickup times around the real speed.
Big fuel savings: usually a sign of a truck that burns much more fuel at high speed. Check your mpg inputs against real records before acting on it.
Every mile lost is a mile not earning your rate; see what each mile pays with the rate per mile calculator and set what to ask for with the counter-offer calculator.
If you govern your trucks
Speed affects driver records too; see MVR in trucking for how violations show up and why insurers care. Tracking speed and fuel across units is a job for trucking compliance software and telematics. On our small fleet dispatch desk, each unit's governed speed is on its rules card so appointments fit it. Results are estimates from your inputs.
If you do govern trucks, tell your dispatcher and your brokers. Pickup and delivery times quoted at 70 mph won't work at 65, and a late arrival costs more than the fuel the governor saved. Plan appointments around the speed the truck can hold, and the change stays on the right side of the ledger.
Pull a month of ELD data
- Pull a month of ELD data for driving hours and highway share
- Measure mpg at each speed from real fuel and odometer records
- Use your average all-in rate per mile
- Ask your insurer whether governed speed changes the premium
Speed limiter questions
01Is there a federal speed limiter requirement for trucks?
No. FMCSA and NHTSA withdrew the proposed speed limiter rule for heavy trucks in July 2025, so there's no federal mandate. Some fleets, insurers and customers set governed speeds on their own.
02Do speed limiters save fuel?
Lower highway speeds generally improve fuel economy, but how much depends on the truck, load, terrain and aerodynamics. Use your own numbers: compare mpg on weeks at different cruise speeds from your fuel and ELD records.
03How many miles does a speed limiter cost per week?
Only the highway share of driving loses speed. At 52 driving hours with 75% at cruise, dropping from 70 to 65 mph costs about 195 miles a week. City and traffic miles don't change.
04Should a small fleet govern its trucks?
It's a business decision. A lower governed speed can mean fewer miles and less revenue, but also less fuel, lower wear and sometimes better insurance terms. Run your own numbers before deciding.
05Do lower speeds reduce wear and tear?
Many fleets report less brake and tire wear at lower highway speeds, but it varies with routes and driving. Track your own repair costs per mile before and after any change.
Plan the load around the speed
We plan pickup and delivery times that fit each unit's real speed and hours.
4% for 2+ trucks, 5% for one, 7% while your MC is new