Why the S550 Is Worth Your Attention

The sixth-generation Mustang (S550, 2015–2023) represents a major leap forward for the nameplate: independent rear suspension, a sophisticated chassis, and a range of engines from the EcoBoost four-cylinder to the ferocious Shelby GT500. As these cars age into the used market, they offer tremendous performance value — but like any used vehicle purchase, due diligence is essential.

Engine Options at a Glance

  • 2.3L EcoBoost (4-cyl): ~310 hp, great daily driver, good fuel economy, solid reliability
  • 5.0L Coyote V8 (GT): 435–460 hp depending on year, the crowd favorite
  • 5.2L Voodoo (GT350/GT350R): 526 hp, flat-plane crank, high-revving masterpiece — premium price
  • 5.2L Predator (GT500): 760 hp supercharged, ultra-premium, lowest supply

Common Issues to Look Out For

All S550 Models

  • IRS subframe bushing wear: Listen for clunking from the rear under acceleration or on rough roads. Bushing replacements are common on higher-mileage cars.
  • Transmission issues (manual): The MT82 6-speed (early cars) has a reputation for notchy, balky shifting when cold. The MT82D4 (post-2019 GT) improved this significantly — ask which transmission is in the car.
  • Infotainment/SYNC glitches: Check that the touchscreen, Bluetooth, and backup camera all function properly.

EcoBoost-Specific

  • Check for intercooler condensation issues — sometimes causes a lean misfire. A catch can is a common fix.
  • Inspect for signs of boost leak — cracked charge pipe couplers are not uncommon.

Coyote GT-Specific

  • On pre-2018 GTs, check for phase actuator noise (a ticking or rattling at startup) — Ford issued TSBs and some replacements for this.
  • Ask about tune or mod history. An already-modified GT isn't necessarily a red flag, but you deserve to know exactly what's been done.

GT350-Specific

  • The Voodoo engine can consume oil under track use — check service records for oil changes and ask about track use history.
  • Verify the brake fluid has been changed if it's a track car. GT350R especially.

Your Pre-Purchase Inspection Checklist

  1. Pull a vehicle history report (Carfax or AutoCheck) — look for accident history, title issues, and the number of previous owners.
  2. Inspect all four body panels and the roof for paint overspray, panel gaps, or color mismatches suggesting prior collision repair.
  3. Start the engine cold and listen for ticking, knocking, or rough idle before it warms up.
  4. Take it on the highway — check for vibrations, pull to one side, or transmission issues.
  5. Inspect the tires: uneven wear patterns can signal alignment or suspension problems.
  6. Look under the car for fluid leaks, damage to the exhaust, or evidence of heavy off-road/curb contact.
  7. Test every electronic feature: windows, heated seats, lane-keeping, adaptive cruise (if equipped).
  8. Have a trusted mechanic do a pre-purchase inspection — especially important for GT350s and GT500s given their value.

Best Value Years to Target

For a daily-driver GT, 2018–2020 model years hit the sweet spot: the updated Coyote engine with improved VVT, the better MT82D4 transmission on later cars, and modern safety technology — all at prices that have come down meaningfully from new-car territory. For EcoBoost buyers, any year works well; the engine is fundamentally solid across the generation.

Whatever you choose, the S550 platform rewards informed buyers. Do your homework, inspect carefully, and you'll get one of the most enjoyable sports cars available at its price point.