Mod note - As of 7/25/2018: We've had quite a few "Hey, come use this CDP. It's great" type of posts. When the CDP doesn't give a good discount, but is only posted to try to get renters to use the CDP of someone so the poster can earn perks from their Hertz Corporate account. From here out, please put the company/trade group/etc that's associated with the CDP or we'll delete the post to keep it on-topic here

NOTE: CDPs provided because Hertz or entity publicly links to them (source links provided next to each CDP). DO NOT list corporate codes or list a CDP without public source link
HERTZ PUBLIC CDPs: (usable by everyone)
CDP# 2007815: Travelers 50 and over (Hertz Fifty Plus) link here
CDP# 2115632: Cyber Sale (not always active for discounts, used during, 2022 & 2023 Cyber Sales, link here)
CDP# 1392782: Hertz Member Program (for members of Hertz Gold Plus Rewards Program - free to join)
CDP# 2102513: Promo Rates (autoslash link here)

MARKETING ORGANIZATION PUBLIC CDPs (usable by everyone - NOTE: these organizations earn commissions and/or perks from Hertz when their CDPs are used)
CDP# 1742729: RentalPerks (free registration link here and CDP link here) (RentalPerks is powered by CorporateShopping.com, registration link here)
CDP # 2235259: Launching Deals (free to use, site link here, Hertz link here)
CDP# 2002325: Save Around Members (sells coupon books with Hertz CDP and offers add'l savings) CDP provided because Hertz links to it publicly here
CDP# 1731619: Entertainment Book (14 day free trial, link here) - CDP provided because Hertz links to it publicly here

CREDIT CARD CDPs: (look in your wallet to see which credit card(s) you have, and where the cc is issued from). You are entitled to use that CDP for your Hertz rental however it should be noted Hertz T&Cs state: "In all cases, XXX card must be registered as the form of payment in your Gold Plus Reward membership profile." So it would be wise to book & pay for your rental with the card CDP you use.
Mastercard:
CDP# 1795034: World Elite Cardholders (EMEA) (link here)
CDP# 795089: World Elite Cardholders (Ireland) link here (link includes CDPs for all other Mastercard card types for Ireland)
CDP# 542075: World Elite Cardholders (France) link here (link includes CDPs for all other Mastercard card types for France)
CDP# 795093: Platinum cardholders UK & Ireland based (link here)
CDP# 795090: World Cardholders UK & Ireland based (link here)
CDP# 814540: Premium cardholders; World & Platinum Credit and Debit (UK Based) (link here)
CDP# 795094: Gold Cardholders (Europe based) (link here)
CDP# 795091: Standard Cardholders (EMEA link here, Ireland link here, France link here)
CDP# 795092: Small & medium sized enterprises (small business cardholders) (Ireland link here)

Visa:
CDP# 1244810: Visa Classic Cardholders (US Based) link here
CDP# 618583: Visa Classic Cardholders (Europe based) link here
CDP# 83181: Visa Classic Cardholders (Asia based) link here
CDP# 769985: Visa Infinite/Signature debit and credit Cardholders consumer & business (EMEA based - DPs here) (link here)
CDP# 2150933: Visa Infinite US Based (link here)

American Express:
CDP# 705500: Basic Cardholders (Worldwide) link here (UK) and here (US) and here (Global)
CDP# 427346: American Express Membership Rewards Members (CDP provided by Hertz for Amex MR Certificate redemption but likely works without redemption, ymmv)
CDP# 1889146: American Express Card Members (autoslash link here)
CDP# 306613: Amex Open Savings ("The OPEN Savings benefit is built into Business Cards from American Express OPEN"; link here)
CDP# 211762: Platinum (US Based) link here
CDP# 633306: Platinum (EMEA Based) link here (Canada) link here
CDP# 1460754: Platinum (Latin America Based) Hertz link here (Amex link here)
CDP# 651060: Platinum Business Card (Italy) link here (link includes CDPs for Italian Gold and Green Business Cards)
CDP# 716953: Air France/KLM American Express Platinum Card (link here) Link also provides CDPs for AF/KLM Silver/Gold Amex cards.
CDP# 591064: Centurion (Black Card) (pdf link here)

Bank Specific:
CDP# 160005: Citibank Mastercard holders (link here)
CDP# 2118295: China Union Pay Credit Diamond Card Holders (link here) Link also provides CDPs for Platinum, Gold, & Classic card holders
CDP# 804483: HSBC Premier World & HSBC Premier World Elite Mastercards US Based (link here)
CDP# 1752376: HSBC Credit Cardholders (Singapore Based link here)
CDP# 2054551: JCB Platinum Cardholders (link here)

LOYALTY PROGRAM CDPs: (require joining the appropriate loyalty program - all are free to join so CDPs are listed)
Airline US Based
CDP# 321739: Alaska Airlines Mileage Plan Members (link here)
CDP# 217692: American Airlines AAdvantage Members - note, AA solely promotes Avis/Budget now. (link here)
CDP# 165385: Delta SkyMiles Members - exclusive with Hertz as of Jan 30 2023 (link here)
CDP# 1790143: Jetblue TrueBlue Members (link here)
CDP# 205418: Southwest Airlines Rapid Rewards Members (link here)
CDP# 062455: United Airlines Mileage Plus Members - note, as of 2023 United exclusively promotes Avis/Budget (autoslash link here)

Airline Non-US Based
CDP# 1039946: Cathay Pacific Green Members (link here) - Link also provides CDPs for Cathay Silver/Gold/Diamond levels
CDP# 739924: KLM Passengers (link here) - Link also provides CDPs for all Air France Flying Blue levels
CDP# 645970: Lufthansa Miles & More Members (link here)
Link to the current list of Hertz add'l airline partners and CDPs here

Hotel
CDP# 154080: Marriott Rewards Members (link here)
CDP# 22754: IHG Rewards Club Members (link here)
CDP# 902517: Accor ALL Live Limitless Members (link here)
CDP# 826779: Accor ALL Classic Members (link here)
CDP# 826680: Accor ALL Live Gold Members (link here)
CDP# 826777: Accor ALL Live Platinum & Diamond Members (link here)
CDP# 2061209: Caesars Rewards Members (link here)

Rail
CDP# 1229959: Amtrak Guest Rewards Members (link here)
CDP# 652500: Deutsche Bahn - DB BahnCard (link here)

MEMBERSHIP CDPs: (These companies require membership but anyone can enroll for a fee). CDPs not listed where not linked publicly by Hertz - you will receive your CDP after joining/buying
CDP# (see link): AAA - Active membership required and the Hertz website checks for active enrollment
CDP# 32796: BJ's Wholesale Club ($55 per year, enrollment link here) Hertz link here
CDP# (provided after joining): Blue Cross Blue Shield Blue 365 Deals: ~20 States offer a Hertz CDP to members if you have health insurance with BCBS. Current participating States a/o Dec 2023 are: Alabama, Arizona, Arkansas, Iowa, Florida, Kansas, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New York (only Western & Central NY, Utica and Rochester regions), North Carolina, Rhode Island, South Dakota, Tennessee, Virginia, & Wash D.C. See here for complete list of participating BCBS that participate in Blue365.
CDP#: (provided after joining): Founders Card ($595 but provides a variety of air/hotel discounts that offer add'l value, link to benefits here)

ASSOCIATION CDPs: (No Qualification to Enroll, i.e., anyone can join) Oftentimes rates are similar among associations anyone can join. As such, you want to pay the lowest annual/monthly fee).
CDP# 2181835: National Auto Sport Association ($69 annually; link here)
CDP# 1916601: Orienteering USA: ($35 annual membership; link here)
CDP# 584703: Touring Club Italiano (link here) (99€ annual membership for Non-Italians). CDP offers 10% off monthly rentals in Italy and abroad.
CDP# 2245010: USA Archery ($20 annual recreational membership, link here). USA Archery partners with PerkSpot to provide Hertz discounts (link here). Logon link here (accessible after enrollment). Add'l Associations partner with PerkSpot such as USA Triathlon ($50 af) and Kiwanis. After joining you'll be given access.
CDP# 15757: United States Equestrian Federation (free to join for fans, registration link here) Hertz link here
CDP# (differs by Alumni Assoc): Your University Alumni Association (Annual fees differ. Some offer car rental codes - ymmv)

ASSOCIATION & UNION CDPs: (with Membership Requirements) These Associations require you to qualify to join. CDPs are provided since Hertz or Association publicly links to them
CDP# 10232: Aircraft Owners & Pilots Association (link here)
CDP# 11657: American Bankers Association (link here)
CDP# 13000: American Bar Association (link here) (Note: non-lawyers can join for $150 per year a/o Dec 2023, join here)
CDP# 42371: American Dental Association (link here)
CDP# 11356: American Institute of Architects (link here)
CDP# 12353: American Institute of Certified Public Accountants (link here)
CDP# 11635: American Medical Association (link here)
CDP# 166639: American Psychological Association (link here)
CDP# 1605257: Freelancers Union (Free to join; link here) Note: CDP shows as Working Today Inc which is the non-profit parent of Freelancers Union
CDP# 182806: National Association of Realtors (link here)
CDP# 50655: National Education Association (link here)
CDP# 2102007: Service Employees International Union (SEIU) Members (link here)
CDP# 205666: Union Plus (link here)

MILITARY CDPs: (require USA military affiliation). CDPs provided since Hertz or military organization publicly link to them
CDP# 83086: Association of the United States Army (pdf benefits link here)
CDP# 157299: Hertz Military rate (link here)
CDP# (use link): Navy Federal Credit Union
CDP# 71822: Reserve Organization of America (link here)
CDP# 77694: USAA (link here)
CDP# 1615021: USBA - Uniformed Services Benefit Association (link here)
CDP# 1264103: Veterans Advantage ($59.95 p/yr, enrollment link here - 20% discount promos provided often reducing price to $47.96 p/yr) (Hertz link here)