Actually the car is not impenetrable at all, only being 450K usd the car is nice to be sure, but there is a VERY simple way to get into it.
Plant lifts on a street and have enough people to defend them,
The car drives over lift and have a blockade come up infront.
Using two lifting pillars lift the car from the handy 5 inch steel bottom they installed so his nice new tires are useless ass soon as you get them off the ground.
Have a team run in with a plasma cutter and cut the window (armor piercing bullets may not get through, but still easy enough to melt through in a matter of seconds with the right equipment.)
In goes a grenade and look the president has no where to go to since he is stuck in his super secure vehicle which due to his security will be his grave.
As tedious as this sounds it could be accomplished literally in a matter of seconds, and with a few rockets the cia officers following his car are taken care of and so is the rest of his escort.
Sorry nothing is impenetrable. Nice car yes, but if someone really wanted him dead, he'd be dead.