2015 Audi RS4 Avant

Premium

Best for buyers who want the B8.5 platform without chasing every option. Expect the core engine, quattro hardware where equipped, and the cleanest entry price.

Most useful when condition and service history matter more than gadget count.

Premium Plus

The sweet spot for most used-car shoppers. This is usually where lighting, MMI, and package availability get materially better without jumping all the way to top trim pricing.

Usually the best value trim to search first on A4, A5, allroad, and Q5-family cars.

Prestige

Stacks on the heavier tech and comfort layer, plus the packages enthusiasts often want when they are trying to avoid retrofit projects later.

Worth it if you specifically want the higher-spec interior and driver-assist bundle.

S models

S4, S5, and SQ5 move into the supercharged 3.0T lane with stronger cooling, bigger brakes, and a higher baseline for suspension and driveline hardware.

The right place to start if your build plan includes tune, dual-pulley, or brake upgrades.

RS models

RS5 and market-specific RS4 Avant are the top-expression B8.5 cars. They bring wider-body intent, more aggressive wheel and brake needs, and less room for cheap shortcuts.

Search these when you want the highest-output factory hardware, not the cheapest power-per-dollar.

Oil capacity

2.0T cars: about 4.6 L / 4.9 qt. 3.0T cars: about 6.8 L / 7.2 qt. RS5 4.2 FSI: about 9.7 L / 10.2 qt.

Coolant notes

Roughly 10.0 L on 2.0T car layouts, 12.0 L on most 3.0T sedan and SUV layouts, and 15.0 L on RS5

Wheel and tire sizing

245/40R18 and 255/35R19 are common performance packages, with Q5-family fitment stepping into taller SUV sizes

Spark plugs

Match plugs to engine code before ordering or tuning: CAED / CPMB 2.0T, CTUB / CTUD 3.0T, CFSA 4.2 FSI

Torque specs

Wheel bolts are typically 120 Nm / 89 lb-ft. Treat major suspension fasteners as repair-manual territory because many are torque-to-yield.

Engine codes

CAED and CPMB on 2.0T, CTUB on S4 / S5, CTUC on Q5 3.0T, CTUD on SQ5, CFSA on RS5 V8

Gear ratio notes

8-speed Tiptronic opens with 4.714:1 and cruises at 0.667:1 in eighth; S tronic starts at 3.692:1 and finishes at 0.519:1 in seventh

Tow capacity

Q5-family cars can be equipped around the 4,400-lb range. Sedans and coupes are usually searched for cargo or fitment, not towing.

Water pump and thermostat housings

Coolant smell, low-level warnings, or crusting around the front of the engine are common first checks on the 2.0T and supercharged 3.0T cars.

Owners usually pair the pump, thermostat, and fresh coolant service together.

Carbon buildup

Direct-injection intake valve deposits can show up as rough idle, cold-start stumble, or a car that feels flatter than it should on the top end.

Most relevant on higher-mileage 2.0T, 3.0T, and RS5 4.2 FSI ownership paths.

PCV and crankcase ventilation

Idle quality changes, lean codes, oil seepage, or strange vacuum behavior often point owners toward the PCV path early.

Especially common on the 3.0T cars when boost leaks and crankcase issues start blending together.

Ignition coils and misfires

Intermittent misfire under load, rough cold starts, or tune-sensitive stumbles usually keep coils and plugs high on the shortlist.

Worth checking before parts-swapping deeper into fuel or sensor work.

Oil consumption on older 2.0T cars

Some owners still research piston-ring history, updated PCV parts, and whether a specific car has already had the problem addressed.

Important buying-context question on used A4, A5, allroad, and Q5 2.0T cars.

S tronic and driveline service

Harsh low-speed behavior, delayed takeoff, or maintenance-history gaps usually push owners toward the DSG / S tronic service record first.

The right first move is service confirmation, not guessing at a failing transmission.

Intake and exhaust

Good first step if you want more sound and cleaner service access without immediately changing the whole character of the car.

Low drama on A4, A5, S4, S5, Q5, and SQ5. RS cars benefit more from quality and fit than volume alone.

ECU tune

The fastest performance-per-dollar move on the 2.0T and 3.0T cars. It changes how the whole platform feels more than most bolt-ons do.

Best paired with fresh plugs, good coils, and a cooling system that is already healthy.

Intercooler or heat exchanger

Important once you are pushing the turbo 2.0T or supercharged 3.0T harder, especially if the car sees heat, traffic, or repeated pulls.

More useful than cosmetic mods when the goal is repeatable performance.

Suspension refresh

B8.5 cars reward quality dampers, alignment, and bushing health before extreme ride-height changes.

The platform feels better with a sorted refresh than with a cheap drop.

Brake upgrades

Pads, fluid, and rotor selection matter immediately. Big-brake kits make sense once the wheel plan is locked.

Check spoke clearance before buying anything for S and RS cars.