1. Select scenarios. Use the chip bar at the top of the input panel to toggle which fuel types are active. All active scenarios are computed simultaneously and compared side by side. Diesel is the natural baseline — it will appear in all outputs as the reference point.

2. Set fleet parameters. Enter your fleet size, analysis period, annual mileage per vehicle, and discount rate in the Basics section. All NPV calculations use the discount rate you specify. Fuel price escalation has been removed from most fuel types to keep comparisons on a flat-price basis — electricity escalation for BEV is retained since utility rate trajectories are relatively well-forecast.

3. Configure vehicle inputs. Purchase prices, residual values, and incentives are per vehicle. For biodiesel B100, the Vector System hardware and subscription costs are included in the vehicle capital line item in the cost breakdown — they are not shown as a separate row but are fully included in the NPV model.

4. Review the TCO tab. Summary cards show fleet lifetime NPV cost and cost per mile. The cumulative cost chart shows nominal (undiscounted) cash outflows over time — it is intentionally monotonically increasing and does not subtract residual value, which is factored only into the NPV totals. The breakdown table shows per-vehicle NPV figures for each cost component.

5. Use the Operational Efficiency tab to model how differences in fueling time, payload capacity, and operational readiness affect effective cost per productive mile. All factors default to 100% (no penalty). Adjust them to reflect your specific fleet operations — a long-haul fleet relying on public CNG infrastructure will have a materially different fueling time score than a depot-fueled fleet.

6. Use the Carbon & LCA tab to evaluate emissions performance. Enter the lifecycle CI for each fuel type using your preferred methodology (GREET, LCFS, RED II). The abatement cost ($/tCO₂e) is a capital efficiency metric: it shows how much extra you pay — or save — per tonne of CO₂e avoided relative to diesel. A negative value means the alternative is both cheaper and cleaner over the analysis period.

NPV engine. All future cash flows — fuel, maintenance, insurance, infrastructure O&M, and Vector System subscriptions — are discounted to present value year by year using the specified discount rate. Residual value is discounted to its present value at the end of the analysis period and subtracted from vehicle capital cost. The formula is standard:

Infrastructure replacement. For CNG stations and BEV chargers (when modeled), if the asset useful life is shorter than the analysis period, replacement costs are added at each replacement cycle, discounted to their NPV at the year of replacement.

Cumulative cost chart. The chart shows nominal (non-discounted) cumulative cash outflows — purchase price plus annual operating costs summed year by year. It does not subtract residual value. This gives a more intuitive view of actual cash commitment over time, distinct from the NPV totals shown in the cards and table.

Operational Efficiency Index (OEI). Three sub-factors (fueling time efficiency, payload efficiency, operational readiness) are combined via geometric mean into a Vehicle Utilization Factor (VUF). Geometric mean is used rather than arithmetic mean because it penalizes a single weak factor more severely — appropriate when any one factor can constrain fleet productivity. Effective miles = stated annual miles × VUF. Adjusted TCO/mile = TCO ÷ (effective miles × years).

Diesel (ULSD)

Baseline scenario. Energy content: 128.5 MJ/gal (lower heating value). Default CI: 94.0 gCO₂e/MJ (EPA GREET 2023, ULSD well-to-wheel). Fuel economy defaults to 8.2 MPG, representing a loaded Class 8 tractor-trailer in mixed-cycle operation. Maintenance cost of $0.12/mi reflects typical heavy-duty diesel drivetrain costs inclusive of oil changes, filters, brake service, and DPF/DEF system maintenance.

Battery Electric (BEV)

Energy content: 3.6 MJ/kWh. Default CI: 33 gCO₂e/MJ (approximate US average grid, ~120 gCO₂e/kWh ÷ 3.6 MJ/kWh). Grid CI varies significantly by region — California (~12 gCO₂e/MJ), Midwest coalier regions (>50 gCO₂e/MJ). Default consumption: 1.75 kWh/mi, appropriate for a Class 8 truck in regional operation. BEV purchase price premium reflects current market pricing for vehicles such as the Freightliner eCascadia and Kenworth T680E. Maintenance savings vs. diesel reflect elimination of engine oil, transmission fluid, exhaust aftertreatment, and fewer brake events due to regenerative braking.

Compressed Natural Gas (CNG)

Energy content: 116.09 MJ/GGE (gasoline gallon equivalent, LHV basis per DOE AFDC). Default CI: 79.2 gCO₂e/MJ (fossil CNG, GREET). Renewable Natural Gas (RNG) can reach strongly negative CI values (dairy biogas: −150 to −300 gCO₂e/MJ) — adjust the CI slider accordingly. CNG vehicle premium reflects factory-built CNG engines (Cummins Westport L9N, ISX12N). Infrastructure cost set to $0 by default — add station capital if modeling on-site compression.

Biodiesel B100 + Vector System

Energy content: 119.5 MJ/gal (B100 LHV, ~8% below ULSD). While B100's lower energy density would typically produce a proportional fuel economy penalty, the Vector System's advanced fuel management system recovers the majority of this deficit. Optimus Technologies' 1.3 million mile evaluation conducted with ADM Trucking demonstrated real-world fuel economy within ±3% of petroleum diesel. Default fuel economy: 8.0 MPG reflects this recovery on a Class 8 chassis. Default CI: 20.0 gCO₂e/MJ represents soy-based B100 under EPA GREET — tallow and waste-fat feedstocks can achieve 5–15 gCO₂e/MJ. The Vector System is a B100 enablement system comprising a lift pump, ECU, PDM, solenoid valves, and in-cab display, allowing standard diesel engines to operate on 100% biodiesel in all conditions including cold starts. Hardware and installation cost is included in the vehicle capital line item. Vehicle purchase price matches diesel since B100 uses the same base chassis.

HVO (Hydrotreated Vegetable Oil)

Energy content: 126.2 MJ/gal (HVO, ~98% of ULSD). Default CI: 28.0 gCO₂e/MJ (waste fat/tallow feedstock, GREET 2023). Soy HVO: ~30–50 gCO₂e/MJ; palm HVO: ~50–70 gCO₂e/MJ. HVO is a true drop-in — it requires no engine modification, no new fueling infrastructure, and has the same vehicle, maintenance, and insurance profile as diesel. The fuel economy penalty vs. diesel (~1–2%) reflects the slight energy density difference. HVO shares vehicle, maintenance, and infrastructure inputs with diesel in this model.

Carbon intensity & lifecycle analysis

• EPA GREET Model (2023) — Argonne National Laboratory. Primary source for US fuel CI values. greet.anl.gov
• California LCFS Fuel Pathways — California Air Resources Board. Certified CI values for registered fuel producers. arb.ca.gov/fuels/lcfs
• DOE Alternative Fuels Data Center — Energy content, fuel properties, and infrastructure data. afdc.energy.gov
• ICCT, "A comparison of the lifecycle greenhouse gas emissions of European heavy-duty vehicles" (2021)

TCO methodology

• ICCT TCO Calculator for zero-emission trucks — theicct.org/tco-calculator
• NACFE, "Run on Less — Electric" (2022). Real-world BEV Class 8 efficiency data.
• Argonne National Laboratory, "Total Cost of Ownership of Alternative Fuel Heavy-Duty Trucks" (2021). DOE/EE-2372.
• RMI, "The True Cost of Owning a Truck" (2023). Charging infrastructure cost benchmarks.
• Optimus Technologies / ADM Trucking, "Immediate Decarbonization: A 1.3 Million Mile Evaluation of 100% Biodiesel in Heavy-Duty Fleets" (2023). Primary source for B100 + Vector System real-world fuel economy data, demonstrating performance within ±3% of petroleum diesel. optimustec.com

Fuel pricing

• EIA Weekly Retail Diesel Prices — eia.gov/petroleum/gasdiesel
• DOE AFDC Alternative Fuel Price Report — CNG and propane retail pricing by region. afdc.energy.gov/fuels/prices
• Biodiesel Magazine / USDA AMS — B100 wholesale pricing data.
• EIA Electric Power Monthly — Commercial and industrial electricity rates by state. eia.gov/electricity/monthly

Vehicle pricing & incentives

• EPA SmartWay — Heavy-duty vehicle fuel economy and certification data. epa.gov/smartway
• IRS Notice 2023-29 — Alternative fuel vehicle credits and 45Z clean fuel production credit guidance.
• CARB ACT Regulation — Advanced Clean Trucks incentive programs and manufacturer sales requirements.
• Optimus Technologies — Vector System product specifications. optimustec.com