my speedomter reads higher than i'm actually going. how do we correct this

What is your question?

i nwas driving down the highway and getting passed by cars. speedometer read 85. took my phone and put it on google maps and the reading was 78. how do we or i fix this

What makes this problem better or worse?

nothing

How long has your 2005 Ford Explorer Sport Trac had this problem?

since i bought it from Holmes tuttle ford in jan 2020