1. Fixed WMI: "MG3" (constant).
2. VDS: Built from three input fields:
   • Vehicle Type Code (e.g. "M2")
   • Battery Capacity Code (e.g. "L")
   • Vehicle Model Code (e.g. "MBM")
3. VIS: Constructed as:
   • Year code "S" for 2025 (map your production year to letter)
   • Location code (e.g. "J")
   • Serial number: a 5-digit zero-padded sequence, unique per year+location.

Sample Python code (inside your Odoo model):

from odoo import models, fields, api

from datetime import datetime

class Vehicle(models.Model):

    _name = 'your_module.vehicle'

    _description = 'Vehicle'

    vehicle_type_code = fields.Selection([...], string="Vehicle Type Code")  # e.g. 'M2'

    battery_capacity_code = fields.Selection([...], string="Battery Capacity Code")  # e.g. 'L'

    vehicle_model_code = fields.Selection([...], string="Vehicle Model Code")  # e.g. 'MBM'

    production_year = fields.Integer(string="Production Year", default=lambda self: datetime.now().year)

    production_location_code = fields.Char(string="Production Location Code")  # e.g. 'J'

    vin = fields.Char(string="VIN", compute="_compute_vin", store=True, readonly=True)

    @api.depends('vehicle_type_code', 'battery_capacity_code', 'vehicle_model_code', 'production_year', 'production_location_code')

    def _compute_vin(self):

        for record in self:

            # Map production year to letter, example: 2025 = 'S'

            year_map = {2025: 'S'}  # Extend as needed

            year_code = year_map.get(record.production_year, 'X')  # Default 'X' if unknown

            # Serial number generation - find max serial for same year + location

            domain = [

                ('production_year', '=', record.production_year),

                ('production_location_code', '=', record.production_location_code),

            ]

            existing_vins = self.search(domain)

            max_serial = 0

            for v in existing_vins:

                if v.vin and len(v.vin) >= 17:

                    serial_str = v.vin[-5:]

                    if serial_str.isdigit():

                        max_serial = max(max_serial, int(serial_str))

            new_serial = str(max_serial + 1).zfill(5)  # zero padded 5 digit

            # Compose VIN

            wmi = "MG3"

            vds = (record.vehicle_type_code or '') + (record.battery_capacity_code or '') + (record.vehicle_model_code or '')

            vis = year_code + (record.production_location_code or '') + new_serial

            record.vin = wmi + vds + vis

The VIN is automatically computed combining WMI + VDS + VIS.

Serial numbers increment uniquely per production year and location.

Extend year_map as needed for other years.

Use dropdowns for the codes (Selection fields) to restrict inputs.