Leon drives 100 miles in 2 hours. How far can he drive in 2 hours and 40 minutes?

Leon drives 100 miles in 2 hours, so he drives an average of 100/2 = <<100/2=50>>50 miles per hour.

If Leon drives for 40 minutes, he drives 40/60 = 2/3 hour.
Therefore, in 2 hours and 40 minutes, Leon can drive 2 + 2/3 = 8/3 hours.
In 8/3 hours, Leon can drive 8/3 * 50 = <<8/3*50=133.33333333333334>>133.33 (rounded to 2 decimal places).
Therefore, Leon can drive approximately 133.33 miles in 2 hours and 40 minutes. Answer: \boxed{133.33}.