6. A Porche is driven 1.6 times as fast as a BMW. If the difference between their speeds is $45 \mathrm{~km} / \mathrm{h}$, how fast is the Porche driven?

Step 1 ：Let the speed of the BMW be denoted as x km/h. Then the speed of the Porche is 1.6x km/h.

Step 2 ：The difference between their speeds is given as 45 km/h. So, we can write the equation: \(1.6x - x = 45\)

Step 3 ：Simplify the equation: \(0.6x = 45\)

Step 4 ：Solve for x: \(x = \frac{45}{0.6} = 75\)

Step 5 ：Calculate the speed of the Porche: \(1.6 \times 75 = 120\)

Step 6 ：\(\boxed{\text{The Porche is driven at 120 km/h}}\)