Which consumes more fuel: a car with 5 passengers or 2 passengers?

[AustinDella]

A car with 5 passengers will consume more fuel than one with 2 passengers. The greater the weight a vehicle carries, the more power it consumes. Comparatively, driving with 5 passengers is more fuel-intensive than driving with just two. Fuel consumption calculation method: By resetting the mileage data on the vehicle's dashboard, the onboard computer automatically calculates the fuel consumption based on the recorded mileage and fuel consumption data. Definition of constant-speed fuel consumption: Constant-speed fuel consumption refers to the fuel consumption per 100 kilometers obtained by certain types of vehicles during constant-speed driving fuel consumption tests as stipulated by national standards. During road tests, it is necessary to follow the national standards for test conditions, methods, road selection, etc. Test conditions include: the load of the test vehicle, the accuracy of test instruments, fuel, tire selection, ambient temperature, humidity, air pressure, wind speed, etc.

[MarcusFitz]

From a physics perspective, increased vehicle weight directly impacts fuel consumption. When carrying five passengers, the total vehicle weight rises significantly, requiring the engine to burn more fuel to propel the wheels and overcome additional inertia and frictional resistance. This effect becomes particularly noticeable during uphill climbs or rapid acceleration, where engine load spikes sharply, combustion efficiency drops, and fuel consumption increases markedly. In daily driving, the difference is less pronounced in urban stop-and-go traffic, but highway tests show full occupancy can increase fuel consumption by over 10%. Through multiple personal road tests, I've observed approximately 2 liters more fuel consumed per 100km when traveling with five passengers. Generally, every 100kg weight increase raises fuel consumption by about 5% - an unavoidable consequence of the law of energy conservation. So when carrying full passenger loads, your fuel expenses will inevitably be fuller too.

[MaximusFitz]

As an ordinary car owner, I've personally experienced changes in fuel consumption during daily driving: with five people in the car, the vehicle noticeably feels heavier, requiring harder throttle presses for acceleration, resulting in higher engine RPMs and louder engine noise, naturally leading to increased fuel consumption. On highways, the fuel gauge drops faster; last time when fully loaded with cargo, the fuel consumption was nearly 1 liter per 100 kilometers higher than with just two people. Increased weight also slightly raises wind resistance, and aggravated tire rolling resistance leads to an overall decrease in fuel efficiency. For short trips, the difference might only be a few cents, but the cost accumulates significantly on long-distance journeys with full occupancy. Regular drivers all know this experience—to save fuel, reduce the load when it's not necessary.

[LaFernando]

From a cost-saving perspective, carrying 5 passengers consumes more fuel. The increased weight forces the engine to work harder, burning more fuel and raising expenses. Based on my calculations: every additional 100kg load increases fuel consumption by about 5%. Carrying five people versus two can cost hundreds more in fuel annually. Optimizing vehicle load by avoiding overcrowding during daily driving can yield significant savings—for instance, urban driving with a light load on smooth roads yields minimal fuel consumption. Veteran drivers often emphasize that lighter cars with fewer passengers mean lower fuel costs, and practical experience shows that full-capacity trips require noticeably more fuel per refill. When the economic impact is substantial, it's wiser to reduce load by adjusting travel plans.