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Exterior Components› Body Panels and Components

ECS Tuning

Forged Carbon Fiber Rear Diffuser

$998.99 $578.19 Save $420.80

SKU: ES4490851

In Stock
In Stock
Ships by Sep 13
Free Shipping over $200
$100 Minimum Order
30 Days Return
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The ECS Tuning Forged Carbon Fiber Rear Diffuser is a premium exterior styling upgrade designed for the B8.5 Audi S4 and A4 S-Line models. It enhances the rear appearance with a more aggressive, sporty look.
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The ECS Tuning Forged Carbon Fiber Rear Diffuser is engineered to provide an aggressive and sporty aesthetic upgrade for the rear of your B8.5 Audi S4 or A4 S-Line. It perfectly complements the factory appeal of the facelifted B8 models, setting your vehicle apart. Installation is straightforward and requires no drilling, cutting, or modifications. For a cohesive exterior transformation, ECS Tuning recommends pairing this rear diffuser with their Carbon Fiber Trunk Spoiler and Side Blades.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

Fitment Guaranteed

Don’t gamble
on fit.

Log your build in the MOTORMIA app and we’ll guarantee this part fits your exact setup — or your money back, return shipping covered.

Available on iOS & Android

Specifications

BrandECS Tuning
Part NumberES4490851
CategoryExterior Components

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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