Yr post caught my eye cuz I don't like my own MPG. Anyway, here's what AI Grok says about it:
"The most common expectation for a
2024 Ford Expedition (and similar Ford trucks/SUVs with 4WD systems) is that
2H (rear-wheel drive only) should deliver slightly better fuel economy than
4A (automatic 4WD) on dry pavement. In 2H, the front driveline components (axles, driveshaft, differential, etc.) are fully disengaged, minimizing parasitic drag and rotational losses.
However, some owners report seeing
better mileage in 4A than in 2H under certain conditions. This isn't the norm (most forums and tests show 2H edging out 4A by a small margin, often 0–2 mpg, or negligible difference), but here are the main reasons it could happen in practice for your Expedition:
- Driving conditions and variables dominate small differences: The drivetrain drag penalty from 4A is very small on modern Ford systems (often <1 mpg in controlled tests, sometimes imperceptible). Real-world factors like temperature, tire pressure, wind, traffic patterns, slight changes in driving style, route, or even the trip computer's accuracy can easily swing results by 1–2 mpg in one direction or the other. If you tested 4A during warmer weather, lighter traffic, or with a tailwind, it could appear better even though 2H is theoretically more efficient.
- Mode-specific throttle/transmission mapping or behavioral changes: Switching modes sometimes subtly alters how the vehicle behaves (e.g., pedal sensitivity or shift points), even if not officially documented. Some owners note that staying in 4A feels smoother or encourages lighter throttle inputs, indirectly improving economy. (This is anecdotal and not a designed fuel-saving feature.)
- Hybrid-like bias in some interpretations (less likely for Expedition): In a few Ford discussions (mostly F-150 PowerBoost hybrids), people speculate that 4A might bias toward front-wheel drive in certain scenarios, and FWD can be marginally more efficient than RWD on some vehicles due to weight distribution or driveline losses. However, the Expedition's system is a torque-on-demand setup that defaults primarily to rear-biased (RWD) in normal cruising and only sends torque forward as needed—so this doesn't typically apply and wouldn't make 4A better.
- Measurement quirks or confirmation bias: Trip computer estimates can vary based on recent driving history. If you reset the computer right before switching modes, or if one test included more highway vs. city, that could explain it. Hand-calculated fill-up-to-fill-up MPG is more reliable for comparison.
In official Ford guidance and most owner reports for the Expedition and similar platforms (F-150, Bronco, etc.),
2H is recommended for best fuel economy on dry roads, while 4A is fine for mixed/wet conditions with minimal efficiency penalty. If you're consistently seeing noticeably better numbers in 4A over multiple tanks/identical routes, it might be worth checking for any drivetrain issues in 2H (e.g., incomplete front axle disconnect) or logging more controlled data.
Overall, any real difference is tiny—usually within normal variation—and not something to stress over unless you're hyper-miling. Many Expedition owners run 4A year-round with no meaningful MPG hit."
