GAS MILEAGE AND TIRES

Fuel economy is how much fuel your vehicle uses to cover a given distance. In Canada it is expressed in litres per 100 kilometres, so a lower number is better. Natural Resources Canada publishes ratings for city, highway, and combined driving. Real-world figures vary with driving style, load, weather, and tire condition.

It depends entirely on vehicle class. A compact sedan may achieve around 7 to 8 L/100 km combined, a mid-size SUV closer to 9 to 11, and a full-size pickup higher again. Compare your vehicle against its own official rating rather than against a universal number, and track whether it is drifting worse over time.

Significantly, and it is the cheapest fix available. An underinflated tire deforms more with each rotation, increasing rolling resistance and requiring more engine effort. That penalty applies to every kilometre. In Canada the effect is seasonal, because cold weather drops pressure and many drivers do not top up until spring.

They can, if you choose a low rolling resistance model and the tires you are replacing were worn, underinflated, or a high-resistance design. Rolling resistance varies meaningfully between models in the same size. New tread is slightly deeper and can add a small amount of resistance at first, which settles as it breaks in.

Slightly, yes. Winter compounds and more aggressive tread patterns typically have higher rolling resistance than summer or touring tires. The trade is worth it for the grip, and keeping them correctly inflated recovers much of the difference. Running them past the point where temperatures rise above 7°C costs you both fuel and tread life.

Driving style is the biggest factor: rapid acceleration and hard braking waste energy on every cycle. Excess weight, roof racks and boxes that create drag, and extended idling all add up. Cold weather itself reduces efficiency through engine warm-up and denser air. Combined with correct pressure, smooth driving delivers the largest total improvement.