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Fleet Fuel Comparison Calculator

Compare total cost and emissions across diesel, CNG, LNG, propane, and electric for commercial fleet vehicles

Free fleet fuel comparison calculator for fleet managers, sustainability coordinators, and transportation planners who need to evaluate the true cost of switching part or all of a commercial fleet to alternative fuels. Enter your fleet size, vehicle class, annual mileage, and current fuel cost. The calculator compares diesel, compressed natural gas (CNG), liquefied natural gas (LNG), propane autogas, and battery electric across total fuel cost, maintenance cost, infrastructure cost per vehicle, well-to-wheels emissions (CO2, NOx, PM2.5), and break-even fleet size for infrastructure investment. Uses diesel gallon equivalent (DGE) and gasoline gallon equivalent (GGE) for apples-to-apples fuel cost comparison.

Pro Tip: The break-even fleet size for CNG infrastructure is the number most fleet managers underestimate. A time-fill CNG station with a small compressor costs $400,000-$800,000 installed, and a fast-fill public-access station runs $1.5-$3 million. If your fleet is under 20 vehicles, the per-vehicle infrastructure cost often wipes out the fuel savings for 5+ years. Electric fleets have a similar dynamic: a single DC fast charger costs $100,000-$250,000 installed, and utility service upgrades can add another $50,000-$500,000 depending on the site. Always model the infrastructure amortization into your per-mile cost before committing.

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Fleet Fuel Comparison Calculator
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How It Works

  1. Define Your Fleet Profile

    Enter the number of vehicles, vehicle class (Class 3-8 or light-duty), average annual miles per vehicle, and current fuel type. The calculator loads default fuel economy values by vehicle class that you can override with your actual fleet data.

  2. Enter Fuel Prices

    Input current prices for diesel ($/gal), CNG ($/GGE or $/DGE), LNG ($/DGE), propane ($/gal), and electricity ($/kWh). The calculator converts all fuels to a common energy basis using DGE so you can compare cost per mile directly.

  3. Set Infrastructure and Conversion Costs

    Enter or accept defaults for fueling infrastructure cost (station, chargers, utility upgrades), vehicle incremental cost (price premium over diesel baseline), and expected infrastructure life. The calculator amortizes infrastructure cost across fleet size and project life.

  4. Review Comparison Results

    The output shows cost per mile, annual fuel cost, annual maintenance cost, infrastructure cost per vehicle per year, total annual fleet cost, and well-to-wheels emissions for each fuel option. A break-even chart shows the minimum fleet size where each alternative fuel becomes cheaper than diesel on a total-cost basis.

Built For

  • Fleet managers evaluating CNG or propane conversion for refuse trucks and transit buses
  • Logistics companies comparing battery electric Class 8 tractors against diesel for regional haul routes
  • Municipal fleet coordinators preparing alternative fuel feasibility studies for city council approval
  • Sustainability teams calculating Scope 1 emissions reductions from fleet fuel switching
  • School districts evaluating propane or electric school bus conversions with grant funding

Assumptions

  • Fuel economy values are based on EPA and DOE published data for the selected vehicle class.
  • Maintenance cost differentials are based on NREL fleet study composite data.
  • Well-to-wheels emissions use ANL GREET model factors for fuel production and combustion.
  • Infrastructure costs are national average installed costs from DOE Clean Cities reports.

Limitations

  • Does not model route-specific duty cycles or terrain effects on fuel economy.
  • Does not account for vehicle availability or downtime differences between fuel types.
  • Electricity demand charges for fleet charging are not modeled (use average blended rate).
  • Resale value differences between fuel types are not included in the cost comparison.

References

  • DOE Alternative Fuels Data Center (AFDC) - Fuel Properties Comparison Table
  • NREL - Financial Analysis of Battery Electric Transit Buses (2024)
  • ANL GREET Model - Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation
  • EPA eGRID - Regional Emission Factors for Electric Vehicle Analysis

Frequently Asked Questions

Diesel gallon equivalent (DGE) is a unit that converts alternative fuel quantities to the energy content of one gallon of diesel (approximately 139,000 BTU). One DGE of CNG is about 137.3 cubic feet at standard pressure. One DGE of LNG is about 1.55 gallons. One DGE of propane is about 1.54 gallons. For electricity, one DGE is about 40.7 kWh. Using DGE allows direct cost-per-mile comparison across fuels without converting efficiency ratings. Gasoline gallon equivalent (GGE) is similar but based on gasoline energy content (about 120,000 BTU).
Battery electric vehicles have the lowest maintenance cost, typically 40-60% less than diesel. No oil changes, no diesel particulate filter (DPF) regeneration, no DEF fluid, no exhaust aftertreatment maintenance, and regenerative braking extends brake life to 2-3 times that of diesel. CNG vehicles have moderately lower maintenance than diesel (10-20% less) because natural gas burns cleaner, reducing engine wear and extending oil drain intervals. Propane is similar to CNG. LNG maintenance is comparable to diesel because the engines are similar in complexity.
Well-to-wheels emissions for EVs depend entirely on the electricity grid mix where the vehicle charges. Use the EPA eGRID emission factor for your region (measured in lbs CO2 per MWh) multiplied by the vehicle energy consumption (kWh per mile). For example, a Class 6 delivery truck consuming 1.5 kWh/mile charging from a grid at 800 lbs CO2/MWh produces about 1.2 lbs CO2/mile. The same truck in a region with 400 lbs CO2/MWh grid produces 0.6 lbs CO2/mile. In both cases, this is typically 50-75% less CO2 than diesel. ToolGrit's CO2 Carbon Intensity Calculator can help determine your local grid factor.
The break-even fleet size for CNG depends on the infrastructure type, fuel price differential, and annual mileage. For a basic time-fill station ($500,000-$800,000), a fleet of 15-25 heavy-duty vehicles each driving 40,000+ miles per year typically recovers the infrastructure investment within 3-5 years when CNG is $1.50-$2.00/DGE cheaper than diesel. For light-duty vehicles with lower fuel consumption, the threshold is higher, typically 40-60 vehicles. Fleets below these thresholds should consider public CNG stations (which eliminate infrastructure cost but charge retail prices) or bi-fuel conversions that maintain diesel capability.
Yes. The EPA Clean School Bus Program provides up to $375,000 per electric bus. The Alternative Fuel Vehicle Refueling Property Credit (Section 30C) provides 30% of fueling infrastructure costs up to $100,000 per location. Many states offer additional incentives: California's HVIP program provides $45,000-$120,000 per zero-emission truck, and New York's Truck Voucher Incentive Program offers similar amounts. The DOE Alternative Fuels Data Center (AFDC) maintains a database of all federal and state incentives by fuel type and vehicle class. This calculator does not model specific incentives but shows where to input them as cost offsets.
Disclaimer: This calculator provides estimated cost and emissions comparisons based on national averages and user inputs. Actual costs depend on local fuel prices, fleet utilization patterns, infrastructure site conditions, and available incentives. Consult fleet management specialists for procurement decisions. ToolGrit is not responsible for financial or operational outcomes.

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