Hi,
Add these fields by inheriting the account.move the model and extending the account.report_invoice_document template
Refer the following code
class AccountInvoiceInherit(models.Model):
_inherit = "account.move"
insurance_customer_id = fields.Many2one('res.partner',string='Insurance Customer')
car_model = fields.Many2one('fleet.vehicle',string="Car Model")
<template id="report_invoice_document_inherit_unit" inherit_id="account.report_invoice_document">
<xpath expr="//div[@class='page']" position="inside">
<div t-if='o.partner_id'>
<b>Insurance Company:</b>
<span t-field="o.partner_id"/>
</div>
<div t-if='o.insurance_customer_id'>
<b>Insurance Customer:</b>
<span t-field="o.insurance_customer_id"/>
</div>
<div t-if='o.car_model'>
<b>Car Model:</b>
<span t-field="o.car_model"/>
</div>
</xpath>
</template>
Regards