Interact with the MMI infotainment system, which consolidates all communications, navigation, entertainment and other functions into a single interface. Though relatively rare, some owners have reported issues with non-functionality of several system components, a hassle that’s more likely if the previous owner has spilled double-double all over the flat-mounted command console. Ensure the controller dial or pad works as intended with all commands as a bare minimum. Twist the dial, tap it forwards, backwards, left and right, and press down on it, ensuring all commands are recognized. If any aren’t, you’re looking at reduced functionality until the controller is replaced.

This one’s important: confirm, twice, that the slightly-used S4 you’re considering still has a powertrain warranty. A hearty portion of S4 owners are naughty and install non-factory software to the engine computer (ECU) to bump the supercharger up to higher-than-factory levels, to make more power. Many folks do this under the belief that setting the ECU back to stock before visiting their dealer will erase any evidence of the tampering, but this isn’t the case. Basically, the ECU has an integrated function that counts how many times it’s been reprogrammed, and so do Audi dealers. If the numbers don’t jive, the dealer knows the S4 in question has been re-flashed with non-Audi software, and the vehicle’s VIN number gets ‘marked’ or ‘flagged’.

Translation? Even if the model you’re considering has run an aftermarket engine management tune and is put back to stock before visiting a dealer, the modification will have been logged, and gives the vehicle in question a so-called TD1 designation, which can void the warranty. So, as part of a pre-purchase checkup, ask the servicing Audi technician to determine if the model in question has been flagged, and to confirm that its warranty is still in good standing.

The Verdict: Loved for driving dynamics and discreet performance, and likely to be suffering only from minimal problems that are easy to identify and fix, a few-year-old Audi S4 makes a fairly confident used performance sedan bet. Seek an Audi mechanic’s thumbs up on a non-modified unit, or seek out a good deal on a Certified Pre-Owned (CPO) unit at a dealer, confirm that the powertrain warranty is still valid, and shop with confidence.

Here’s some additional reading

And just 2 recalls

Crash Test Ratings:
NHTSA: 5/5 Stars (2013 and up only)

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