The Best All-Rounder: Infiniti Q50 3.7 V6
Undervalued used performance sedans are older high-spec four-door cars that offer strong engines, sophisticated chassis setups, and upscale cabins for the price of, or less than, many new economy-focused vehicles, making them compelling alternatives for drivers who want power and character instead of bare-bones transport.
If you want one used performance sedan that balances pace, comfort, and reliability, the Infiniti Q50 3.7 with its naturally aspirated V6 is the smart buy. The standard 3.7-liter VQ37VHR V6 makes 328 hp and 269 lb-ft of torque, pushing the Q50 from 0–60 mph in about 5.3 seconds and on to a governor-limited 155 mph. This V6 sports sedan shares its all-aluminum engine with the 370Z and loves to rev to a 7,000 rpm peak, with one of the best-sounding mainstream V6 soundtracks. Compared with newer turbo variants, the simpler non-turbo layout cuts complexity and long-term risk. The platform’s rear-drive dynamics and upscale interior make it feel far more special than a new economy car, while used prices have dropped into cheap luxury car territory, turning the Q50 3.7 into an undervalued sports sedan gem.
Cons to know: early Q50s can suffer from premature brake wear, infotainment glitches, occasional transmission issues, and moonroof drain problems that cause water stains or damp carpets if not fixed. As with any older luxury sedan, maintenance records matter more than mileage: service history for oil changes, transmission fluid, and cooling components should decide your shortlist. If you want traditional steering feel, avoid cars with the Deluxe Touring Package, which bundles Direct Adaptive Steering steer-by-wire tech. If you can live with those caveats, this Q50 3.7 is the best value choice for most buyers who want reliable pace.
The Tech-Lover’s Choice: Acura RL with SH-AWD
For drivers who care more about clever engineering and all-weather grip than outright engine size, the second-generation Acura RL is the standout undervalued sports sedan. Its 3.7-liter transverse-mounted V6 produces 300 hp and 271 lb-ft of torque, sent through a five-speed automatic transmission. On paper, those numbers look modest next to modern turbo monsters, but the magic is in Acura’s Super Handling All-Wheel Drive torque-vectoring system, which was benchmarked against high-end exotics and delivers Ferrari-style cornering composure at family-car prices. "The second-generation RL is one of the more overlooked bargains in the used luxury sedan market". That means you get a quiet, refined cabin, strong safety focus, and advanced driveline tech for far less than a new mainstream sedan with a basic engine.
The RL is ideal if you want a discreet, comfort-oriented sleeper that still feels special when the road turns twisty. As a cheap luxury car, it offers a long equipment list and a solid Honda-derived V6 that is known more for durability than drama. Being a complex all-wheel-drive sedan, the key downside is age-related wear in its drivetrain and electronics; budget for preventative maintenance on SH-AWD components and stay away from neglected cars. Focus your search on examples with full service history and smooth shifting from the five-speed auto. Get a pre-purchase inspection that checks for fluid leaks, suspension bushing wear, and any warning lights. If those boxes are ticked, the RL’s blend of comfort, stealth performance, and advanced torque vectoring makes it the pick for enthusiasts who want sophistication over raw noise.
The Wildcard: Audi S6 V10 Sleeper
If you want maximum drama per dollar and accept higher running costs, the C6 Audi S6 is your wildcard. It hides a 5.2-liter naturally aspirated V10 derived from the same architecture as the Lamborghini Gallardo’s engine. In S6 trim it delivers 429 hp and 398 lb-ft of torque through a 6-speed automatic and Quattro all-wheel drive. According to one report, "That makes the S6 one of the most affordable V10-powered cars on the market". From the outside, it looks like an ordinary mid-size executive sedan; on the move, it revs past 7,000 rpm and sounds like a supercar. This is the textbook definition of a sleeper: discreet styling, huge power, and four-door practicality, a perfect fit if your idea of cheap luxury cars involves big engines and subtle looks.
However, you must go into S6 ownership with open eyes. The V10 is tightly packaged and complex; timing chain and tensioner wear is common and sits at the rear of the engine, turning repair into an engine-out job. Owners also report oil consumption, carbon buildup on intake valves, and failed coil packs. In other words, this is not a low-maintenance daily commuter. When shopping, treat maintenance history as critical: you want records showing regular oil changes, quality fuel and oil, and carbon cleaning. Have a specialist check for timing-chain noise, misfires, and warning lights before buying. If you can handle higher upkeep, the S6 offers an experience no new economy car can touch: a Lamborghini-related V10 in a mid-size sedan shell, making it one of the most outrageous used performance sedans on the market.
Key Buying Checks for Used Performance Sedans
Whether you lean toward the Infiniti Q50, Acura RL, or Audi S6, the same core rules apply when hunting for undervalued sports sedans. First, prioritize maintenance history over odometer readings: for any 10-plus-year-old luxury sedan, evidence of regular oil changes, transmission servicing, and cooling-system care matters more than mileage alone. Second, avoid cars with missing records or obvious deferred maintenance; unseen issues can quickly wipe out any savings.
Third, be aware of model-specific systems and weaknesses. If you dislike steer-by-wire, seek Q50s without the Deluxe Touring Package and its Direct Adaptive Steering. On the S6, timing chain wear is one of the most common complaints and demands engine-out work if neglected. Budget for an independent inspection focusing on drivetrain noises, fluid leaks, and electronic faults. Finally, remember that these used performance sedans were premium cars when new; running costs will still reflect their high-performance engines and complex features. If you go in prepared, each of these cars delivers performance and engineering quality that rivals or beats many new mainstream sedans, while costing a fraction of the money upfront.
Buy if / Skip if
- Buy the Infiniti Q50 3.7 V6 if you want a reliable V6 sports sedan with strong performance and lower complexity than modern turbo engines.
- Skip the Infiniti Q50 3.7 V6 if you are sensitive to potential infotainment glitches, brake wear, or dislike the feel of steer-by-wire systems.
- Buy the Acura RL if you value sophisticated SH-AWD torque vectoring, a 300 hp V6, and a refined but underrated cheap luxury car package.
- Skip the Acura RL if you are unwilling to maintain an older all-wheel-drive system and prefer a simpler front-drive or rear-drive sedan.
- Buy the Audi S6 V10 if you want a Lamborghini-related 5.2-liter V10, Quattro traction, and an ultimate sleeper among used performance sedans.
- Skip the Audi S6 V10 if you are on a tight maintenance budget or worry about timing chain, oil consumption, and carbon buildup issues.
- Buy the Infiniti Q50 3.7 V6 if you want the best all-round balance of performance, comfort, and ownership peace among these undervalued sports sedans.
- Skip the Acura RL if you prioritize raw exhaust drama over subtle engineering and prefer a louder, higher-revving engine character.
- Buy the Audi S6 V10 if you already own or plan to use a specialist mechanic and accept higher running costs as the price of drama.
- Skip the Infiniti Q50 3.7 V6 if a brand-new, warranty-backed mainstream car matters more to you than performance and character.
