Prescott, Arizona → Oshkosh, Wisconsin → Prescott, Arizona

The cleanest speed comparison came from Return Leg 1 with ProPower off and LightShip HVAC off. At 62 ± 2 mph, the truck returned 15.56 MPG; at 67 ± 2 mph, it returned 15.14 MPG. The faster band reduced MPG by 2.7%, raised hourly fuel use from 3.97 to 4.35 gal/hr, and increased mean engine load from 61.6% to 72.8%.

The aggregate MPG is useful for operating-cost and range planning, but it is not a pure vehicle-efficiency coefficient. The campaign intentionally varied ProPower state, TrekDrive state, speed, temperature, altitude, route, canopy condition, and battery-support configuration.

Figure 1 · Overall fuel economy by recorded travel segment

The July 14 TrekDrive calibration loops are excluded from point-to-point trip totals. The first two July 11 files are short early-day recordings; the long July 11 file provides the principal Williams-to-Salida record.

Figure 2 · All-trip pooled bands versus the cleaner Return Leg 1 comparison

The all-trip pooled speed bands are strongly confounded by different grades, winds, ProPower states, temperatures, and gears. The Return Leg 1 comparison is preferred because both bands occurred on the same day with ProPower and LightShip HVAC off.

The two measured converter-output channels integrated to 86.5 kWh AC over the travel campaign. At the project's measured baseline conversion of 7.70 kWh AC/gal, this corresponds to 11.23 gallons of generation fuel.

This allocation is best treated as a trip-level energy budget and commercialization metric. It does not prove the truck would have burned exactly 11.23 fewer gallons with ProPower off because engine operating point, hybrid-battery behavior, grade, wind, and enrichment can change when the electrical load is removed.

Figure 3 · Maximum valid logged temperatures across the campaign

The low external AC output during the Floyd Hill warning argues against appliance overload, but it does not rule out a local inverter, converter, wiring, or enclosure-temperature threshold. The later successful Vail Pass climb supports reducing sustained climb speed when thermal margin is limited, but route, ambient temperature, grade profile, traffic, cooling airflow, and preconditioning all differed.

Separate LightShip charging-interface issue

The campaign also documented a distinct LightShip-side NACS/AeroHub thermal limitation. Charging stopped near the 102-105°F receptacle/EVSE range and resumed after cooling, with evidence of a possible restart lockout period. This must remain separate from the Ford ProPower shutdown in later fault-tree analysis.

This summary uses the complete uploaded set of point-to-point OBD travel recordings and excludes the July 14 calibration loops from trip totals. OBD trip counters provide segment distance and fuel; the two converter-output PIDs provide ProPower energy.

Several factors prevent a single pooled regression from being treated as a definitive vehicle model: incomplete synchronized wind data, differing grade profiles, wide temperature variation, changing ProPower and HVAC states, the July 16 canopy-up anomaly, and Battery Boost usage on the return.

• Matched-condition ProPower incremental-GPH model: refine the 0.64-0.65 gal/hr commercialization metric.
• Cruise-speed model: include wind, grade, temperature, and ProPower covariates.
• Floyd Hill event reconstruction: define thermal precursor thresholds and operating guidance.
• NACS/EVSE thermal study: separate ambient heat soak, current heating, and restart lockout.
• Measured-lambda enrichment analysis: quantify the hot-weather/open-loop fuel penalty.
• Energy-balanced TrekDrive analysis: pair truck fuel saved with LightShip battery energy spent.