Utilise their Panic Button. The driving agent should then focus on driving, Whilst either the Mayor or another SS agent describes the situation down government text radio.
Evasive driving manouvers should be deployed, However avoid going on the wrong side of the highway at any period as doing so puts yourself, the Mayor, Your team and other road users at extreme risk, and makes police response significantly more difficult.
If the Secret Service agents are split between vehicles, The vehicle not carrying the Mayor could be used.
Splitting the Secret Service between different vehicles as so you are more spread out, and agents can block and confront such attackers.
The Limousine possesses a huge amount of weight and power capable of deflecting and withstanding an attack of this nature.