Whaddya do?

I have to drive across the Benicia Bridge, toll is $4.00(freak'n) dollars. In line- waiting to pay the toll. 

Car in front takes forever. I sigh. Turn up the radio.  Ho hum! Finally my turn, I pull up, flash the $4 dollars. Toll taker waves me through.

What?!!! 

"The car ahead of you paid for you" he says.

Sheesh- I used to do that when the toll was a BUCK! People still do that? 

I try to catch up to the car in front of me... it's going really fast. I weave through traffic to keep them in sight. They are way ahead of me.

Now what? Do I break the law so I can wave and mouth the word 'Thanks' at 75 miles per hour?Or... do I take the risk of being thought a Cretin by the Car In Front by not catching up? And now I can't just pass them... that would seem kinda weird.  What if I just drive excessively fast and pass them, without any acknowledgement? What kind of a jerk would I be then? 

Jeez!- All for four freakin' dollers!