You are driving a motor vehicle with a manual gearbox. What style of driving results in higher fuel consumption within a built-up area?

In a built-up area, fuel consumption rises mainly when the engine has to produce a lot of power unnecessarily.

Answer 1 (“accelerating heavily”) increases consumption because hard acceleration demands high torque and often requires enrichment of the fuel-air mixture. You also spend more time in lower gears where the engine works less efficiently, and any speed you gain is usually lost again soon due to the next junction, traffic lights, or traffic flow.

Answer 2 (“driving at high engine speed”) increases consumption because higher RPM means more engine cycles per second, more internal friction and pumping losses, and generally worse efficiency. In city traffic, staying in a lower gear and revving the engine uses noticeably more fuel than shifting up early.

Answer 3 (“driving in a high gear”) does not by itself increase fuel consumption. As a rule of thumb, shifting up early and driving with low RPM in the highest suitable gear saves fuel, as long as the engine doesn’t “lug” (shudder) and you can still accelerate safely when needed.