Vehicle overheats when driving it at higher rates of speed.

What is your question?

After driving the car for about 10-15 minutes the vehicle starts to raise in temperature at higher rates of speed. Accelerating the car to 80mph causes the temperatures to rise. Having the car set to 75mph on cruise control and driving uphill also causes it to start rising in temperature. Generally keeping it at 70mph or lower does not cause over heating. By turning on the heat in vehicle causes the vehicle to not overheat even at speeds of 80mph or more.

What makes this problem better or worse?

Problem does not occur when vehicle heat is on. Problem is worse when vehicle is accelerating.

How long has your 2013 Hyundai Sonata had this problem?

About 2 months.