A car travels 150 miles using 5 gallons of fuel. If the fuel efficiency decreases by 10% due to heavy traffic, how many gallons will the car use to travel 300 miles under these conditions?

Tue, 05 May 2026 20:47:17 +0000

**How Fuel Efficiency Shifts Impact Your Trip: What to Expect on Longer Journeys** When summer road trips stretch over 150 miles with smooth highway driving, many wonder: what happens to fuel needs when traffic slows and efficiency drops? Understanding how real-world conditions affect fuel use helps travelers plan better—whether saving money or avoiding unexpected stops. The average car achieves about 30 miles per gallon in ideal conditions. At 150 miles using 5 gallons, this confirms a reliable 30 mpg baseline. But real cities challenge this number, cutting efficiency by 10% or more. When fuel efficiency dips due to stop-and-go traffic, travel demands more gas—yet knowing how this translates into actual fuel use for longer trips is key. **Why Fuel Efficiency Declines in Heavy Traffic** Heavy traffic isn’t just frustrating—it changes how a car consumes fuel. Idling in congestion and frequent stops prevent the engine from maintaining optimal RPM and cycle—both vital for efficiency. The engine works harder, burning more fuel per mile. This drop by 10% isn’t rare; studies confirm fuel economy can fall 10–15% in stop-and-go conditions. The car still runs, but demand rises due to inefficient performance, making longer distances feel heavier on its fuel tank.