Under what circumstances does cruise control consume more fuel in trucks?
3 Answers
Truck cruise control consumes more fuel when going uphill or downhill. Here are the situations where cruise control consumes more fuel: Consumes more fuel on slopes: When going downhill, drivers usually release the accelerator slightly to utilize inertia for coasting, but cruise control does not employ these basic driving techniques. Instead, it maintains a fixed speed regardless of conditions. Similarly, when going uphill, the engine will aggressively increase fuel supply to maintain speed, leading to excessively high engine RPM. Cruise control is designed to maintain a steady vehicle speed, and when the vehicle is moving steadily, it means the driving force is in balance with wind resistance and rolling resistance. Therefore, when wind resistance or rolling resistance changes, the vehicle's driving force must adjust accordingly.
As a long-haul truck driver, I've found that cruise control is particularly fuel-inefficient on mountainous slopes. When climbing, the system constantly accelerates the engine to maintain speed, causing RPM to surge and fuel consumption to spike. On descents, it brakes to limit coasting, wasting fuel-saving opportunities. On continuously undulating roads, cruise control responds sluggishly, resulting in unstable speeds and overall fuel consumption 10-20% higher than manual driving. With heavy truck loads, gradient effects are more pronounced – I've personally experienced fuel consumption rising from the usual 10L to 12L on steep climbs, creating significant additional costs. Now when encountering mountain roads, I turn off cruise control and manually apply gentle throttle modulation for smoother acceleration/deceleration, achieving both fuel economy and stability.
Based on my understanding of automotive technology, using cruise control in trucks during highway driving increases fuel consumption, especially in high winds. Air resistance increases with the square of speed, and when the vehicle exceeds 80 kilometers per hour, aerodynamic drag rises sharply, requiring the engine to maintain high output continuously. The system maintains a fixed speed without allowing coasting, missing opportunities to save fuel. With their large front ends, trucks experience more pronounced wind resistance effects, and fuel consumption spikes even more when fully loaded. From my data comparisons, cruising at 100 kilometers per hour on flat roads consumes 1-2 liters more fuel than at 90 kilometers per hour. I recommend setting a reasonable speed and adjusting according to traffic conditions rather than relying blindly on cruise control.
