Mercedes-Benz R320 front turn signal bulbs use 3357NA or 3457NA size, while rear turn signal bulbs require 12496 size. The replacement chart covers 2007 through 2009 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz R320 front turn signal uses two different bulb types across its model years, with the 3457NA fitted to 2007-2008 models and the 3357NA fitted to the 2009 model.
The 3457NA and 3357NA are both T25 wedge-base bulbs operating at 12V, but they are not interchangeable. The 3457NA carries a dual filament rated at 27W and 7W, while the 3357NA carries a single filament rated at 27W only.
The dual-filament design of the 3457NA allows it to serve two lighting functions from a single socket, typically combining a turn signal function with a secondary running or parking light function.
Both the 3457NA and 3357NA feature natural amber glass, which produces an amber-colored output without the use of a colored lens or housing filter.
The 3457NA and 3357NA are designated under the ANSI standardization system, which is the governing standard for automotive bulbs in the United States and Canada.
Installing a 3357NA in a socket designed for a 3457NA would result in the loss of the secondary filament function, as the single-filament 3357NA cannot replicate the dual-filament behavior of the 3457NA.
The rear turn signal bulb for the R320 is the 12496 across all three model years, 2007-2009, indicating no change in rear fitment over the production span covered by these specifications.
The 12496 is a Philips/Osram part number rather than an ANSI-standardized designation, which means it is a manufacturer-specific bulb not directly cross-referenced within the standard ANSI numbering system.
The 12496 is classified as a specialty halogen application bulb operating at 12V, a voltage consistent with standard automotive electrical systems.