Yup, it sure does. 
But, there is a dichotomy of sorts here. The less distance you have to travel, the less speed matters... so we must look at the median of average need vs. safety, and gas mileage.
75 might actually be a good number, but we would have to look at statistics such as automobile accidents due to speeding, and fuel cost, vs the benefits gained on average from travelling at 75 mph... and compare the findings to what happens at 55 mph.
