What's an "ordinary" highway according to you? Interstate 95 has a 65 MPH speed limit, if I remember correctly. The beltlines around DC do, as well, although there are parts where it'll slow down, and there always seems to be construction going on, so anticipate that. And if you're traveling through anytime other than between 1 a.m. and 4:30 a.m., traffic will be so thick that you won't get anywhere near the speed limit once you pass the outer beltline. Coming from the south, D.C. backups very often extend all the way to Fredericksburg, and, coming from the north, you can anticipate it being rough pretty much from the Baltimore metro all the way through the DC metro.
Your average speed on the turnpike should be greater than on a highway.
55 miles per hour.
3 hours
3 hrs.
The gas mileage for the highway, depending on the year is 25 miles per hour. It can get 13-17 miles per hour in the city.
Information Highway?
Highest A+
2 hours 54 minutes.
If your on a highway without traffic - about an hour.
92 minutes = 1 hour 32 minutes
An hour and twenty minutes.
55 miles per hour.