Way to unlock: You need to complete main mission 74 (The Big Score) And select the Obvious variant towards the end of that mission. There is no marker for this mission on the map and you can start it anywhere.
Playable characters: Michael
Additional information: Earlier, there were two similar missions but, this one requires you to perform specific missions without offering as much freedom as the previous ones.
The plan assumes obtaining some four-door car where, in accordance with the piece of information from Lester, this needs to be some larger vehicle so, I would recommend some SUV.
It would be a good idea to make an additional, optional, stop at the Los Santos Customs garage to customize the car a bit. This is so, because you are going to use the car to escape a pretty demanding police pursuit. The list of the purchases recommended by me includes an Armor Upgrade - the most expensive one would be best, and Bulletproof Tires. Both of these upgrades are going to cost you a dozen or so thousand dollars and, although it is not mandatory, it will make things easier towards the end of the heist.
Regardless of whether you have decided to make the upgrades or not, you need to contact Lester. Select him from your contacts list and confirm your readiness to use the stolen car (Getaway vehicle ready - the above screenshot). You can now reach the marked underground parking lot. Leave the car and walk away from here
Rewards for the completion of the mission: none
Requirements for the completion of the mission in 100%: There are no additional requirements for this mission, so it gets completed in 100% automatically.