Genuine, OEM and aftermarket parts: what’s the difference?

The same part can come in three different boxes at three different prices. What does each mean, and when should you choose which?

The first question a Mercedes owner faces when searching for a part is usually not price but confusion: genuine, OEM, aftermarket. All three look “compatible”, but they are not the same thing.

A genuine part is the one the manufacturer boxes with its own star logo. OEM is made by the same factory but sold under the supplier’s brand rather than the manufacturer’s — often the exact same product. Aftermarket is made by independent producers as an equivalent; its quality varies greatly by brand.

A practical rule: for items that directly affect safety and engine life (brakes, timing, gaskets), choose genuine or a known OEM. For visible exterior panels and low-risk items, aftermarket can be a sensible saving. At Er Benz we state the available options and price differences openly on every item and leave the decision to you.