Four words get used interchangeably in listings that are not interchangeable in fact: genuine, OEM, OE and aftermarket. The confusion is rarely accidental. Here is what each one means, and — more usefully — which questions cut through the labelling.
The four terms
| Term | What it means | What it costs |
|---|---|---|
| Genuine | In the vehicle manufacturer's box, sold through its dealer network | Highest |
| OEM / OES | Made by the company that supplied the assembly line, sold in its own box | Mid to high |
| OE-specification aftermarket | Built to the original specification by another factory | Mid |
| Aftermarket | Made to fit and function, specification set by the manufacturer — not by the carmaker | Low to mid |
The important boundary is between the last two rows. An OE-specification part is built to a specification that came from the original design. A generic aftermarket part is built to fit the hole and do the job, to a specification the factory wrote for itself. Both can be perfectly serviceable. Only one of them can honestly be described as equivalent to the original.
Who actually makes the parts
Vehicle manufacturers do not make most of their parts. They buy them from tier-one suppliers who also sell into the open market. A water pump, a mount or a compressor on a German saloon very often carries the mark of a supplier whose name never appears on the car — Bosch, ZF, Lemförder, Mahle, Valeo, Continental, Hella, Sogefi, Sachs and others.
This is why the genuine-versus-aftermarket argument is often the wrong argument. If the same factory made both, the difference is the box, the channel and the price — not the component. The productive question is which factory.
'OE quality' is not a standard
Three questions that get a real answer
- 01Can you cross-reference it to the OE number? A supplier who knows the part knows its number and can tell you what it supersedes. "It fits a W205" is not an answer.
- 02What is the warranty, in writing, and who pays the freight? Warranty against manufacturing defects is the baseline. The interesting part is the second half: if it fails, who covers the labour and the shipping.
- 03Can I see the actual part? Real photographs from real stock, not a catalogue render. If every image on a site is a render, the seller may not hold the stock at all.
We are an aftermarket supplier built to OE specification, and we say so on every page. We are not an authorised dealer for Mercedes-Benz, BMW or any vehicle manufacturer, and we do not sell anything as genuine that is not. See what we supply and what we promise.
Common questions
- Is an OEM part the same as a genuine part?
- No. A genuine part comes in the vehicle manufacturer's packaging and is sold through its dealer network. An OEM part is made by the same supplier that produced it for the assembly line, but sold in the supplier's own box. Same factory, different channel and usually a different price.
- Does 'OE quality' mean anything?
- Not in any enforceable sense. It is a marketing phrase with no standard behind it. Ask instead who wrote the specification, what the material is, and what the warranty covers in writing.
- Are aftermarket parts legal to fit?
- Yes in most markets, and in many jurisdictions the vehicle manufacturer cannot require you to use its own parts for service work outside the warranty period. What matters commercially is whether the part meets the specification and who stands behind it.
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