Answer :
Yes. 55mph equals 88.5139 kmph. in 8 hours, you will have traveled slightly over 700 kilometers.
Yes indeed ! You sure can. This is your lucky day.
500 kilometers is about 310.7 miles.
In order for you to cover that distance in 8 hours, you only need to average
about 38.8 mph . If you stop along the way ... for food, gas, rest, pits, etc. ...
then you'll have to drive a little faster to keep up your average. But by managing
your stops, you can certainly do it without ever exceeding 55 mph.