If I understand your story correctly it makes good sense why the Silverado didnt beat you.
You were already doing 70mph when you saw the SS working his way through traffic.
When the SS attempts to get next to you your accelerating past70mph and you only later line up at a higher speed. (80-85mph?)
At this speed you are now next to each other and attempt to make a run .
The Silverado is speed limited to 109mph which is lower than our own speed limiter. Basically all you had to do was accelerate 25mph past the speed you were currently running before his speed limiter kicked in and shut his speed down.
I am a bit curious though as I've often heard our trucks are limited to 115mph, though your story sounds like you were running up to and possibly past 120.
Specs on the SS
ACCELERATION (Seconds)
Zero to 30 mph: 1.9
40 mph: 3.0
50 mph: 4.6
60 mph: 6.3
70 mph: 8.3
80 mph: 10.7
90 mph: 14.8
Street start, 5-60 mph: 6.8
Top-gear acceleration, 30-50 mph: 3.4
50-70 mph: 4.3
Standing 1/4-mile: 14.8 sec @ 90 mph
Top speed (governor limited): 109 mph
http://www.caranddriver.com/article....&page_number=2