As an automotive expert with a deep understanding of the mechanics and physics involved in high-speed driving, I can provide you with a detailed explanation of how speed is achieved in a car and the factors that influence it.

Firstly, it's important to understand that the speed of a car is not only determined by its horsepower but also by a variety of other factors including, but not limited to, its aerodynamics, weight, transmission efficiency, and tire grip. The relationship between speed and power is not linear, and it becomes increasingly difficult to increase speed as it approaches the limits of these factors.

Aerodynamics play a significant role in high-speed driving. As a car moves faster, it has to overcome more air resistance, which increases exponentially with speed. This is where the rule of thumb you mentioned comes into play. The power required to overcome air resistance is directly proportional to the cube of the speed, which means that to double the speed, you need eight times the power, not four times as the rule of thumb might suggest.

Weight is another critical factor. A lighter car requires less power to achieve the same speed compared to a heavier one. This is why many high-performance cars are designed with lightweight materials and components.

Transmission efficiency is also crucial. The transmission system must efficiently transfer the power from the engine to the wheels. Any loss in this process reduces the car's ability to reach higher speeds.

Tire grip is essential for maintaining speed, especially in high-performance driving. Tires must have sufficient grip to maintain traction and prevent slipping, which is particularly important when accelerating or cornering at high speeds.

Now, let's delve into the specifics of the rule of thumb you mentioned. While it is a simplified way to understand the relationship between speed and power, it does not accurately represent the complex dynamics at play. The actual power required to achieve a certain speed is influenced by the aforementioned factors and can vary greatly depending on the specific car and conditions.

For example, if a car can reach 50 mph with 35 horsepower, it doesn't necessarily mean that it would require 140 horsepower to reach 100 mph. The power required would be significantly higher due to the increased air resistance and other factors. Similarly, reaching 200 mph or 300 mph would require a substantial increase in power, but the exact figures would depend on the car's design and capabilities.

In conclusion, the speed a car can achieve is a complex interplay of power, aerodynamics, weight, transmission efficiency, and tire grip. While horsepower is a significant factor, it is not the sole determinant of speed. Understanding these dynamics is crucial for anyone interested in high-speed driving and the performance capabilities of cars.

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The rule of thumb for speed and air resistance is that for a given car, it takes four times as much power to go twice as fast. So, if your car can do 50 mph with 35 horsepower, you'll need 140 horsepower to do 100 mph. For 200 mph, you'll need about 560 horsepower. At 300 mph, it would be around 2,240 horsepower.read more >>