Location: this mission becomes available some time after the completion of Extra Commission side mission. Wait until you receive a message from Josh and get to the meeting place with him, at the motel in the Rancho district (the above screenshot). After you get there, listen to the conversation with Berstein and go to the room upstairs. Note - before you start this mission, it is a good idea to equip yourself with a melee weapon (e.g. a baseball bat or a club purchased in the Ammu-Nation store).
During the conversation, Josh will ask you to scare Lenny. You need to get to the estate owned by him, in the Rockford Hills district, and you can either use your own means of transport, or take Berstein's car (Lampadati Felon GT). The important thing is that you drive a fast vehicle. After you get to the Rockford Hills, locate the estate shown in the screenshot and start chasing the green sports car which belongs to Lenny.
Try to keep within small distance of Lenny's car and continue firing at it. Do not try to shoot Lenny, and only damage his car so, aim at the bodywork and not at the windows. After Lenny stops his car, stop next to him and get out of your car. From your inventory, select the melee weapon and use it to hit Lenny. The mission will soon conclude.
Rewards for the completion of the mission: none
Requirements for the completion of the mission in 100%:
- Pulverizer - You need to mug Lenny using any club.
- Seized - you need to stop Lenny's car within 40 seconds. Use some good automatic weapon to conduct fire and make sure you do not shoot the driver by accident.