Why a car of 1500 cc show 180km on the board while another same 220km?

The difference in displayed speeds on the dashboards of two identical 1500 cc cars, one showing 180 km and the other 220 km, can be attributed to several factors. Here are a few possibilities:

1. Tire Size: Car manufacturers use different tire sizes for different models, even if they have the same engine capacity. Larger tires have a larger circumference, which means they rotate fewer times for a given distance compared to smaller tires. This difference in tire size can affect the speedometer reading. A car with larger tires will show a lower speed on the speedometer than a car with smaller tires, even if both are traveling at the same actual speed.

2. Gear Ratio: The gear ratio between the engine and the wheels can also affect the speedometer reading. A lower gear ratio means that the wheels rotate more times for every revolution of the engine. This can result in a higher displayed speed on the speedometer. Conversely, a higher gear ratio means that the wheels rotate fewer times for every revolution of the engine, which can result in a lower displayed speed.

3. Speedometer Calibration: Speedometers are calibrated to display a specific speed based on the tire size and gear ratio of the vehicle. If the speedometer is not properly calibrated, it may display an inaccurate speed. For instance, if the speedometer is calibrated for a smaller tire size than what is actually installed on the car, it will overestimate the actual speed.

4. Error Tolerance: Speedometers are not perfectly accurate instruments and there is always a certain margin of error in their readings. This error tolerance can vary between different vehicles and can affect the displayed speed. For example, a speedometer with a higher error tolerance may show a speed of 220 km when the actual speed is closer to 200 km, while a speedometer with a lower error tolerance may show a speed of 180 km when the actual speed is close to 200 km.

It is important to note that the displayed speed on the speedometer may not always be the exact same as the actual speed of the vehicle. This is because the speedometer is based on calculations using the wheel revolutions, and various factors can affect these calculations, such as tire wear, road conditions, and aerodynamic factors.