This page of the Mafia Definitive Edition guide contains a walkthrough for the Professional Protection side mission available in the Free Ride mode. You will learn where to find the phone box in the Central Island district, how to protect the vehicle and how to destroy the gangsters' cars.
You can learn about this mission by finding Herbert Baskerville's letter in the Free Ride. The letter lies on a large table in the "boardroom" in Salieri's bar.
It has information on where the mission will begin. It is a telephone booth located in the Central Island district, a short distance from the multi-level parking lot. The location of the booth is shown in the pictures.
Try to lower the difficulty to easy – it will be easier to keep the main character alive.
Get on the passenger seat to begin the ride. You must use firearms and protect your vehicle from attacks – Tommy gun, the default weapon in this mission, works best here. Always try to aim at a driver or a vehicle's engine. Don't waste time eliminating gangsters leaning out of windows – Tommy can lose a lot of health points or even die.
It is best to shoot longer bursts – start firing before the vehicle gets close to your car. Remember that your Tommy gun has unlimited ammo in this mission. Unfortunately, you have to prepare for a long, several-minute chase.
The reward for completing this mission is a Gold Tommy Gun. It does not deal more damage, it only has a unique appearance.