# What does signing a car maker's CO2 ambition letter commit an auto parts supplier to?

Canonical: https://senseible.earth/answers/mercedes-supplier-ambition-letter-co2-neutral-parts

Signing Mercedes-Benz's Ambition Letter commits a supplier to deliver only CO2 neutral production materials to Mercedes-Benz by 2039 at the latest. Mercedes-Benz says suppliers that decline to sign will not be awarded new contracts, so the letter decides eligibility now, while detailed terms arrive through purchase contracts.

## What the letter asks for

Under its Ambition 2039 goal of a CO2 neutral new vehicle fleet across the value chain, Mercedes-Benz asked suppliers to sign an Ambition Letter. Signatories agree to supply only CO2 neutral parts to Mercedes-Benz by 2039 at the latest. Mercedes-Benz reports that suppliers covering 84 percent of its annual purchasing volume had signed by 2023, and that suppliers who decline will not get new contracts.

## Where it bites first

- Mercedes-Benz names battery cells, steel and aluminium as its priority materials until 2039, since they cause most of the supply chain CO2 of an electric car.
- Battery cell makers have already been held to renewable electricity: Mercedes-Benz cites CATL and Farasis commitments, and BMW announced in 2020 that the makers of its fifth generation battery cells are contractually bound to use green power.
- For other parts, binding terms such as a renewable electricity share or product footprint delivery through Catena-X come in purchase contracts and supplier standards. Read each nomination letter and contract for them.

## What CO2 neutral will need to mean

Buyers expect reductions first: energy efficiency, renewable electricity and lower carbon materials, with credits only for what remains. ISO 14068-1:2023 sets out how a carbon neutrality claim must be made, with a reduction plan and offsets only for residual emissions. Ask your buyer which definition its contracts use.

## First steps for an Indian supplier

1. Build a Scope 1 and 2 baseline per plant, from a year of electricity bills and fuel invoices.
2. Report Scope 2 both location-based and market-based. Renewable electricity counts only with evidence: rooftop solar generation, group captive or open access contracts with the supplier's documents, or certificates.
3. Prepare product footprints for the part families the OEM buys, since contracts move to per part figures.
4. Set a reduction target with a base year, and keep invoices behind every number.

## What Senseible does here

Senseible calculates Scope 2 per plant from electricity bills, location-based at 0.710 kg CO2 per kWh and market-based where you add instrument data, and prepares self-declared product footprint drafts from uploaded data.

- [Answer a Catena-X PCF request](https://senseible.earth/answers/answer-a-catena-x-pcf-request-auto-parts)
- [ISO 14068 carbon neutral requirements](https://senseible.earth/answers/iso-14068-carbon-neutral-requirements)
- [Group captive solar and Scope 2](https://senseible.earth/answers/group-captive-solar-ppa-scope-2-claim)
- [Automobile sector](https://senseible.earth/industries/automobile)

Sources: [GHG Protocol Scope 2 Guidance (market-based method and quality criteria)](https://ghgprotocol.org/scope-2-guidance), [ISO 14068-1:2023, Climate change management, transition to net zero, carbon neutrality](https://www.iso.org)

Last reviewed 2026-10-18. Checked October 2026 against Mercedes-Benz Group's Ambition 2039 page (84 percent of purchasing volume signed in 2023, priority materials) and BMW Group's 30 June 2020 announcement on green power for fifth generation battery cells; OEM requirements change, so quote only current public documents and your own contract.