You can either play B7 on the 3rd fret or Cmaj7. I prefer Cmaj7

Em                      Cmaj7 B7      Em                     Cmaj7 B7          
driving down this road i see,          the broken hearted memories

of yesterday what will be, but i don't know if it's for me
and this car it aint' going on, he keeps singing that old highway song
what to do, and i'm lost on the highway blue

and i push the gas and felt that sting, and your lost within my memory
and i'll head on out behing that old sky, and out there where the angels cry
what to do, now i'm lost on the highway blue
now i'm lost on the highway blue