1. Reservations
HQ Rental Software
  • Getting started
  • Authentication
  • Base URLs, regions and versioning
  • Errors
  • Responses and pagination
  • HQ concepts and glossary
  • Custom fields and item types
  • Dates, time zones and money
  • Filtering and incremental sync
  • Guide: build a booking engine on your website
  • Guide: connect an OTA or broker
  • Guide: sync your fleet and prices to a website
  • Guide: sync invoices and payments to accounting
  • Guide: sync customers with a CRM
  • Guide: take payments
  • Guide: bill tolls and fines
  • Rate limits and idempotency
  • Webhooks
  • Car Rental
    • Comments
      • List the comments of a record
      • Create a comment
      • Update a comment
      • Delete a comment
      • List the comments of a reservation
      • Add a comment to a reservation
      • Delete a reservation comment
    • Currencies
      • List currencies
    • Emails
      • List email templates
      • Send an email template for a record
      • Send the reservation confirmation email
      • Send the rental agreement email
      • List the email templates of a reservation
      • Send an email template for a reservation
      • Create a quote and email it
    • Addresses
      • List the addresses of a record
      • Create an address
      • Get an address
      • Update an address
      • Delete an address
    • Fields
      • List the fields of a record type
      • Get a field by its column
      • List the customer form fields (booking step 5)
    • Blocked Days
      • List blocked days
    • Customer Credits
      • List the credit transactions of a customer
      • Add credit to a customer
      • Update a credit transaction
      • Delete a credit transaction
    • Fines
      • List fines
      • Create a fine
      • Get a fine
      • Update a fine
      • Delete a fine
    • Packages
      • List package items
      • Get a package item
      • List packages
      • Get a package
    • Quotes
      • List quotes
      • Get a quote
    • Rate Types
      • List rate types
      • Create a rate type
      • Get a rate type
      • Delete a rate type
      • Update a rate type
    • Rates
      • List rates
      • Create a rate
      • Get a rate
      • Delete a rate
      • List rates (v2)
      • Update a rate
    • Reservation Attempts
      • List reservation attempts
      • List reservation attempts by email
    • Extensions
      • List the extensions of a reservation
      • Extend a rental
      • Delete an extension
    • External Charges
      • List the external charges of a reservation
      • Add an external charge to a reservation
      • Delete an external charge
    • Adjustments
      • List the adjustments of a reservation
      • Add an adjustment to a reservation
      • Delete an adjustment
    • Payments
      • List the payments of a reservation
      • Record a payment on a reservation
      • Update a payment
      • Release an offline security deposit
      • Refund an online security deposit
      • Charge the customer's saved card
    • Refunds
      • List the refunds of a reservation
      • Record a refund on a reservation
      • Update a refund
    • Reservations
      • Confirm a reservation
        POST
      • Cancel a reservation
        POST
      • Set a reservation to pending
        POST
      • Set a reservation to quote
        POST
      • Mark a reservation as no-show
        POST
      • Mark a reservation as ready for pick-up
        POST
      • Get the options for the dates step (booking step 1)
        GET
      • Validate dates and list available vehicle classes (booking step 2)
        POST
      • Change the vehicle class of a reservation
        POST
      • List additional charges for a vehicle class (booking step 3)
        GET
      • Price a vehicle class with selected charges (booking step 4)
        POST
      • Create or update the booking customer (booking step 6)
        POST
      • Create the reservation (booking step 8)
        POST
      • Update a reservation
        POST
      • List reservations
        GET
      • Get the rental agreement link
        GET
      • Mark the rental agreement as signed
        GET
      • Get a reservation
        GET
      • Assign a vehicle to a reservation
        POST
      • Detach the vehicle from a reservation
        POST
      • List the vehicles available for a reservation
        GET
      • List the free vehicle class upgrades of a reservation
        GET
      • Apply a free vehicle class upgrade
        POST
      • Upload the driver signature
        POST
      • Upload pick-up or return photos
        POST
      • Search availability and prices for all vehicle classes
        GET
      • List reservations (API v2)
        GET
    • Vehicle Replacements
      • List the vehicle replacements of a reservation
      • Replace the vehicle of a rental
      • Delete a vehicle replacement
    • Reservation Agents
      • List the users that can be assigned as agents
      • Assign the agents of a reservation
      • Assign the return agents of a reservation
    • Seasons
      • List seasons
      • Create a season
      • Get a season
      • Update a season
      • Delete a season
    • Security Deposits
      • List security deposit rules
      • Get a security deposit rule
    • Availability
      • List availability of vehicle classes
      • Get availability of a vehicle class
    • Driver Licenses
      • Read a driver license barcode
      • Save a driver license barcode to a reservation customer
      • Upload a driver license image for a reservation customer
  • Filters
    • List filter types and operators
  • Contacts
    • List contact categories
    • Get a contact category
    • List contacts of a category
    • Create a contact
    • Get a contact
    • Update a contact
    • Merge contacts
  • Fleets
    • Additional Charges
      • List additional charges
      • Get an additional charge
    • Features
      • List features
      • Get a feature
    • Locations
      • List locations
    • Blocked Periods
      • List the blocked periods of a vehicle
      • Create a blocked period
      • Update a blocked period
      • Delete a blocked period
    • Branches
      • List vehicle makes
      • Get a vehicle make
      • List branches
    • Damages
      • List the damages of a vehicle
      • Create a vehicle damage
      • Get a vehicle damage
      • Update a vehicle damage
    • Vehicles
      • Models
        • List vehicle models
        • Get a vehicle model
      • Types
        • List vehicle types
        • Get a vehicle type
      • List the maintenance status of a vehicle
      • List vehicles
      • Get a vehicle
      • Update a vehicle
      • List vehicles for toll matching
    • Relocations
      • Create a relocation
      • Delete a relocation
      • List the relocations of a vehicle
    • Telematics
      • List the OBD readings of a vehicle
      • List OBD readings of all vehicles since a reading ID
      • List the telematics alerts of a vehicle
      • List the trips of a vehicle
      • List vehicle alert types
    • Maintenance
      • List repair orders
      • Create a repair order line
      • Update a repair order line
      • Delete a repair order line
      • Get a repair order
      • List maintenance types
    • Vehicle Classes
      • List vehicle classes
      • Get a vehicle class
  • Payment Gateways
    • List saved credit cards of a customer
    • Delete a saved credit card
    • List payment methods
    • Get a payment method
    • Get a payment button
    • Get a payment transaction by UUID
    • Create a payment transaction
    • Refund a payment transaction
    • Re-check a payment transaction
    • List payment transactions
  • Sheets
    • List sheet items
    • Create a sheet item
    • Get a sheet item
    • Update a sheet item
    • List sheets
    • Get a sheet
  • Files
    • List files of a record
    • Upload a file
    • Delete a file
  • Inventory
    • List inventory categories
    • Get an inventory category
    • Shows a list of inventory items
    • Finds inventory item by id
    • Finds inventory price by id
    • shows a list of inventory purchase order
    • Create purchase order
    • Finds purchase order by id
    • Returns report of purchase order
    • Cancels purchase order by id
    • Finds inventory stock by id
  • Invoice
    • List invoices available as e-invoices
    • Download e-invoices
    • Create invoice item
    • List invoice payments
    • Create an invoice payment
    • Get an invoice payment
    • Update an invoice payment
    • Spread a payment over a contact's open invoices
    • List invoices
    • Create an invoice
    • Get an invoice
    • Email an invoice
    • Void an invoice
    • Download an invoice PDF
  • Audit Logs
    • Lists the audit log entries
  • Countries
    • List countries
  • Taxes
    • List taxes
    • Get a tax
  • Users
    • List users
  • Products
    • Categories
      • List product categories
      • Create a product category
      • Update a product category
      • Delete a product category
    • List products
    • Create a product
    • Update a product
    • Delete a product
  • Schemas
    • RequestBodies
    • Money
    • SaveRepairOrderLine
    • ErrorBusinessRule
    • SaveBlockedPeriod
    • ErrorValidation
    • SaveVehicleDamage
    • ErrorNotFound
    • ErrorUnauthorized
    • ReservationSummary
    • ReservationTotal
    • AvailableVehicleClass
    • AdditionalCharge
    • ReservationOverview
    • ReservationPayment
    • FleetsPageInfo
    • FleetsEmptySuccess
    • VehicleDamage
    • BillingAmount
    • InvoiceLine
    • ReservationRefund
    • CustomField
    • Comment
    • PaginationFields
    • Country
    • CustomFieldAddress
    • FilterDescriptor
    • Tax
    • VehicleClassAvailability
    • CustomerCreditTransaction
    • DriverLicenseData
    • DriverLicenseResult
    • Fine
    • FineInput
    • PackageItem
    • Package
    • Quote
    • RateType
    • RateTypeWrite
    • RatePriceInterval
    • RateRecord
    • RateWrite
    • ReservationAttempt
    • ReservationExtension
    • ReservationAdjustment
    • ReservationStatusResult
    • VehicleReplacement
    • ReservationRecord
    • ReservationListItem
    • ReservationListPage
    • ReservationDetail
    • ReservationOverviewWithVehicles
    • Season
    • SeasonWrite
    • SecurityDepositRule
    • OtaVehicleClassAvailability
    • RateV2
    • ReservationDriverV2
    • ReservationListItemV2
    • ContactCategory
    • Contact
    • ContactInput
    • AttachedFile
    • FleetAdditionalCharge
    • Branch
    • VehicleFeature
    • Location
    • VehicleMaintenanceStatus
    • RepairOrder
    • ObdReading
    • VehicleAlert
    • VehicleTrip
    • BlockedPeriod
    • VehicleMake
    • VehicleClassImage
    • VehicleClassFeature
    • VehicleClass
    • VehicleRelocation
    • VehicleType
    • Vehicle
    • InventoryCategory
    • InvoicePayment
    • Invoice
    • InvoiceDetail
    • SavedCreditCard
    • PaymentGatewaySummary
    • PaymentMethod
    • PaymentTransaction
    • ProductCategory
    • Product
    • SheetItem
    • SheetItemInput
    • Sheet
  1. Reservations

List the free vehicle class upgrades of a reservation

GET
/car-rental/reservations/{reservation_id}/free-vehicle-class-upgrades
Returns the other vehicle classes that have vehicles available for the reservation dates.
An unknown numeric reservation_id does not return 404. An unknown UUID returns 404.

Request

Authorization
Path Params

Header Params

Responses

🟢200OK
application/json
The classes available as a free upgrade. HTTP 200 is also used for failures: always check success. When it is false, the body is an ErrorUnauthorized (status_code 401 or 403).
Bodyapplication/json

Example
{
    "success": true,
    "status_code": 200,
    "errors": [],
    "data": [
        {
            "vehicle_class_id": 5,
            "label": "Full size SUV",
            "sipp_code": "FFAR",
            "recommended": false,
            "image": "https://yourcompany.example.com/public/fleets/images/8d2a1c4e-5f6b-4a7c-9d8e-0f1a2b3c4d5e/vehicle-class",
            "availability": {
                "quantity": 3,
                "limited_availability": false
            }
        }
    ]
}
🟠404Record Not Found
Modified at 2026-10-29 13:52:44
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List the vehicles available for a reservation
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Apply a free vehicle class upgrade
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