The Nuka-Cola Challenge

 is a Fallout 3 side quest connected with the Nuka-Cola soft drink company, and its prototype beverage, Nuka-Cola Quantum. It is also an Xbox 360 and PC achievement and a PlayStation 3 Trophy.

Take Sierra's Nuka-Cola tour
To start this quest, find Sierra Petrovita at Girdershade, which is located west of Jocko's Pop & Gas Stop and SW of Smith Casey's Garage.

Upon finding Sierra Petrovita, she offers you to take the "Nuka-Cola tour," which consists of viewing the large number of Nuka-Cola collectibles she owns. If you agree to take the tour, she will show the player around her home, discuss various Nuka-Cola facts and talk about some of the items in the room. After the tour, she gives the player an Ice Cold Nuka-Cola.

Talk to Sierra
She then asks the player to collect Nuka-Cola Quantums and says she will pay 40 caps for each bottle.

After exiting her house, Ronald Laren will ask the player to instead give him the Nuka-Cola Quantums, as he hopes that giving them to Sierra will improve his chances of "plowing her bean field". He offers to pay the same price for the Quantums, though a successful Speech check will cause him to double the payment. If you have the Black Widow perk, you also have the option to offer a threesome in exchange for him finding the bottles, causing him to eagerly run off to his death. His body can then be found inside the main entrance of the Nuka-Cola Plant.

Recover 30 bottles of Nuka-Cola Quantum
Nuka-Cola Quantums are rare items. There are only 92 total in the base game, and only a dozen or so more with add-ons. They are easy to see because they glow (only if HDR is enabled on the PC version). There is also a ten percent chance of finding one in a Nuka-Cola Vending Machine. For a list of bottle locations, see Nuka-Cola Quantum.

Of course, the Quantum Chemist perk makes this whole task much easier--especially when you are in Sierra's house. She has a large amount of Nuka-Cola all over the place and, as long as you're hidden, stealing the Nuka-Cola's and having them automatically converted into Quantum is easy; however, you will lose karma.

Recover the shipping manifest (optional)
A good place to start looking is the Nuka-Cola Plant. Aside from a few Quantums, you can find a terminal entry with shipping details for Quantum. You can get the code for this terminal from Milo, Shipping Foreman by either passing a Speech check, killing it, obtaining an employee badge by finding the note Welcome to the Nuka-Cola Family! or by using a dialogue choice obtained through the Robotics Expert perk. The code is used in the computer terminal in the room where Milo is found. After using the code, select the option to retrieve the shipping manifest.

The manifest tells the player of three locations where shipments of the Nuka-Cola Quantum were in the process of delivery; these being the shopping center at Paradise Falls, Super Duper Mart, and Old Olney grocery.

At the Super Duper Mart, the shipment of Nuka-Cola Quantum can be found in the back storeroom near the fallen shelves next to the Protectron. There are three of them. It is in the same room as the Emergency Supplies.

In Paradise Falls, the Quantum can be found in Eulogy's Pad underneath the stairs next to a bed. There are five of them. You should also be careful when stealing these Quantums, because if anyone sees you, the whole town will turn hostile towards you. It should also be noted that you will not lose Karma for stealing these as they are the property of Eulogy Jones, since he is a slaver and slavers are evil, you won't lose Karma for stealing it from him.

When investigating Old Olney, you will discover that the shipment of Quantum never made it there. The skeletal remains of the driver can be found on the steps outside a building in Old Olney along with the Nuka-Cola Accident Report. The note reveals that there was an accident and the driver abandoned the truck to look for help (which never came because the bombs fell). The truck with its Nuka-Cola Quantum can be found by exploring the highways surrounding the town. It is found about halfway between Old Olney and Chaste Acres Dairy Farm.

Just for the taste of it (optional)
On the second floor of the Nuka-Cola Plant's office section, the Lone Wanderer can find the body of Winger Mercier. On his corpse will be the Finding the Formula note. The note calls for Winger Mercier to find the secret Nuka-Cola Clear Recipe from the R&D Department of the Nuka-Cola Plant and return it to his partner, Goalie Ledoux, who is awaiting him at the Red Racer Factory.

The formula is inside a locked safe in one of the walls of the R&D Department. The R&D room is the first room on the left as the player enters the Nuka-Cola Plant (there are no signs for the "R&D" department except for the word "RESEARCH" written on one of the walls). The safe requires a key to open. To acquire the key, the player must find the Mister Handy robot named Milo the Shipping Foreman at the lower level of the Factory Floor. The player can pass a Speech challenge to convince the robot to give them the key, or if they have the Robotics Expert Perk, Milo will give it to them automatically. Otherwise, the player can look for a note by the computer in the office next to R&D (Storage and mixing vats) called " Welcome to the Nuka-Cola Family! ", that contains ID data allowing them to pass the ID check. If all else fails, the Lone Wanderer can acquire it in less civilized ways by simply killing the robot.

The Red Racer Factory is only a few miles NE of the Nuka-Cola Plant. Ledoux and two members of his Ice-Gang team will be waiting for the player in front of the factory entrance. Ledoux offers 250 caps for the formula, or the player can try to convince him to give them 400 by passing a Speech challenge. Ledoux only appears while "The Nuka-Cola Challenge" is active (False on PC, if you find the formula and find Mercier, Ledoux will be waiting outside the Red Racer Factory even if "The Nuka-Cola Challenge" quest is not active). After selling the formula to Ledoux, you can kill him to get it back, though there appears to be no incentives.

Reward
Sierra pays you for the Nuka-Cola Quantums (40 caps each). Once you give her enough to fill her Nuka-Cola Vending Machine, she gives you the Schematics - Nuka Grenade, and you get +300 XP. In the future, she will also make you a Mississippi Quantum Pie if you bring her the ingredients.

Giving the bottles to Ronald Laren results in a loss of karma and double the caps (80 caps each) if you succeed in the Speech check, otherwise you get 40. Once the quest is complete (if you gave him 30), he goes to Sierra's house straight away and starts making moves — only to have Sierra completely misunderstand his advances.

For maximum money and good karma, it is possible to give 29 bottles to Ronald, and 30 to Sierra, or vice versa for bad karma. However, a total of 59 bottles is a difficult achievement and will make it very hard to make any Nuka Grenades or Mississippi Quantum Pies, as Nuka-Cola Quantums are semi-rare. (Although if you have the Broken Steel add-on and have the Quantum Chemist perk and possess many Nuka-Colas, it is possible that you can make many Nuka Grenades-especially since Nuka-Cola is restocked in traders inventories every so often)

Behind the scenes

 * The name of this quest is a reference to "The Pepsi Challenge," a taste-test marketing promotion run by PepsiCo since 1975.
 * Sierra is the name of a Soft drink from Pepsi Co., that is the direct competition to Sprite from Coca-Cola.
 * If Sierra is killed, and Ronald is spoken to, a Speech check can be passed in which the player blames the Nuka-Cola Corporation for her death. Ronald will assume it's because the Nuka-Cola machine he got for her had a label saying; "Warning if you tamper with this unit you'll have to answer to the Nuka-Cola Corporation". This dialogue is likely a reference to a scene from the film Dr. Strangelove involving tampering with a Coca-Cola machine.

Bugs

 * After the transaction at the Red Racer Factory, the other members of Sudden Death Overtime will leave and Goalie Ledoux will remain in his spot indefinitely.
 * If you decide to follow the other 'teammates' to their destination (granted the Enclave doesn't take them out along the way) they will reach the Nuka-Cola Plant. Once inside, they'll stay near the entrance and run in place, not actually going anywhere.
 * If you find the Nuka-Cola clear formula, and then drop it before talking to Ledoux, you can still sell it to him for the reward. It is then present in his inventory if you kill him, leaving you with 2 copies once you pick up the one you dropped.
 * When Milo, the Shipping Foreman initially approaches the character asking for confirmation instead he just opens dialogue saying "What is it now? Sir/Ma'am" (Depending on PC gender). Any further attempts to open dialogue result in the same phrase repeated over and over. This may cause "The Nuka-Cola Challenge" to be marked as completed and Goalie Ledoux will not appear at the Red Racer Factory.
 * When a player enters Sierra's house she may start to flee. This means there is no chance of talking to her, making the quest impossible to both start and complete. Also, she seems never to return. It may be possible to work around this bug by saving before entering Sierra's house. If you find she is fleeing, then reload the save and scout the surrounding area for any creatures that may have spawned in or near Girdershade. Kill them and then enter her house. She should no longer be fleeing. It is also possible to talk to her as normal while she is fleeing if the interaction is timed correctly.
 * Sometimes while giving the Nuka Cola tour, Sierra may become stuck, stealing a single bottle of Nuka Cola will force her to continue the tour after a brief protest, however you will lose karma.
 * If you have Fawkes as a companion when entering Sierra's house, he will immediately turn hostile against Sierra for no apparent reason (with no hostiles outside) and hence, can cause Sierra to be killed, failing the quest. Does not always happen, though.

El Desafío Nuka-Cola Погоня за ядер-колой