Segment:
Executive Sedan / Luxury Mid-size Sedan
Brand Perception:
Premium, advanced engineering, quattro all-wheel drive reputation
Key Competitors 1991:
BMW 5 Series (E34), Mercedes-Benz E-Class (W124), Lexus LS 400 (though higher segment), Cadillac DeVille
Drivetrain Options:
Front-wheel drive (FWD) and permanent all-wheel drive (quattro)
Platform Design:
C4 platform, known for robust construction and aerodynamic styling
Interior Quality:
High-quality materials, ergonomic design, advanced features for its time
Powertrain:
Engine mechanical, engine electrical, fuel system, ignition system, exhaust system, transmission (manual and automatic), drivetrain, clutch
Chassis:
Suspension (front and rear), steering system, braking system (including ABS), wheels and tires
Body And Interior:
Body construction, exterior trim, doors, windows, interior trim, seats, climate control system (HVAC), audio system
Electrical And Electronics:
Wiring diagrams, lighting, instruments, charging system, starting system, power accessories, control modules, diagnostic trouble codes (DTCs)
Maintenance:
Scheduled maintenance, fluid changes, filter replacements, lubrication, inspections
Repair And Rebuild:
Engine overhaul, transmission overhaul, component replacement, system diagnostics, electrical repairs, body panel repair
Diagnostics And Troubleshooting:
Step-by-step diagnostic procedures, fault finding charts, symptom-based troubleshooting
Depth:
Comprehensive; covers basic maintenance to complete engine and transmission rebuilds, including detailed electrical schematics and diagnostic procedures
Engine Code And Type:
AAH (2.8L SOHC V6 90°)
Horsepower Ps:
172 PS @ 5500 rpm (approximate, varies slightly by market/spec)
Torque Nm:
245 Nm @ 3000 rpm (approximate)
Fuel System:
Bosch Motronic fuel injection (typically Motronic M2.3 or M2.4)
Ignition System:
Electronic ignition with distributor
Valve Train:
SOHC (Single Overhead Camshaft) per bank, 2 valves per cylinder
Engine Options:
5-cylinder gasoline engines (e.g., 2.3E, 2.3E-20V), 5-cylinder diesel engines (e.g., 2.5 TDI), 2.2L 5-cylinder gasoline (prior to C4 in some markets), potentially turbo variants in some regions (e.g., S4 variants).
Transmission Options:
5-speed manual transmission
Transmission Options:
4-speed automatic transmission (ZF 4HP22 or similar)
AWD System:
Torsen T-3 center differential for quattro models, typically with rear open differential (early models) or optional rear limited-slip differential (LSD).
Manual Transmission Fluid Spec:
API GL-4 or GL-5, SAE 75W-90 (Check manual for exact spec)
Automatic Transmission Fluid Spec:
G 052 162 A1 (or equivalent Dexron-III compatible fluid, consult manual for specific Audi specification)
Crash Test Data Availability:
Limited public data for 1991 models, but designed to meet European safety standards of the era.
ABS:
Anti-lock Braking System (ABS) available/standard on many models
Traction Control:
Traction Control System (ASR - Automatic Slip Regulation) available on some quattro models
Airbags:
Driver-side airbag standard on many models, passenger airbag optional or unavailable depending on market and configuration.
Seatbelts:
Front and rear seatbelts, pre-tensioners for front seatbelts on some models
Body Structure:
Integrated safety cage, crumple zones
Audio System:
Factory AM/FM stereo cassette player, optional CD player, often with premium speaker systems (e.g., Bose on higher trims).
Climate Control Tech:
Manual or optional automatic climate control (Climatronic).
Cruise Control:
Standard or optional cruise control
Connectivity Features:
N/A (No modern connectivity features like Bluetooth or USB)
Headlights:
Halogen headlights, aerodynamic design for the era.
Service Intervals Gasoline
Oil Change Interval:
Typically 10,000 km or 6 months (whichever comes first), though consult the specific manual for precise intervals and oil type.
Spark Plug Replacement:
e.g., 30,000 - 60,000 km depending on plug type (e.g., copper vs. platinum/iridium).
Timing Belt Replacement:
Crucial for V6 and 5-cylinder engines. Typically 60,000 - 90,000 km or 5-7 years. Failure causes catastrophic engine damage.
Diesel Fuel Filter:
Recommended replacement every 20,000 - 40,000 km
Engine Oil Spec:
VW 500 00, 501 01, or 502 00 (depending on specific engine and oil formulation), typically SAE 5W-40 or 10W-40. Consult manual for exact spec.
Coolant Spec:
G 11 specification (blue/green coolant), often a 50/50 mix with distilled water.
Brake Fluid Spec:
DOT 3 or DOT 4
Engine Mechanical:
Timing belt failure (critical), oil leaks from seals and gaskets (valve cover, oil pan), potential for head gasket issues with age.
Electrical:
Degradation of wiring insulation (especially around engine bay), failure of dashboard illumination, HVAC control issues, central locking problems, vacuum hose degradation affecting climate control.
Suspension:
Worn control arm bushings, ball joints, tie rod ends, rear torsion beam bushings (if applicable), strut/shock absorber wear.
Fuel System:
Clogged fuel injectors, failing fuel pumps, aging fuel lines.
Climate Control:
Vacuum leaks affecting mode control, blower motor resistor failure, compressor clutch issues.
Audi Heritage:
Founded in 1910, known for engineering innovation, advanced automotive technology, and performance.
Audi 100 Evolution:
The C4 generation, launched in 1991, represented a significant redesign from the C3, featuring a more rounded, aerodynamic body, improved interior, and upgraded powertrain options, including the introduction of the V6 engine as a primary offering.
Production Period:
1991 - 1994 (for C4 generation Audi 100)
Manufacturing Locations:
Germany (primary), also potentially in other Volkswagen Group facilities.
Evolution To A6:
The C4 generation Audi 100 was facelifted and renamed Audi A6 in 1994, marking a shift in Audi's naming convention.
Industry Recognition:
The C4 generation was generally well-regarded for its build quality, driving dynamics (especially quattro models), and comfort, often reviewed favorably against its German and Japanese luxury competitors.
Reliability Perception:
Mixed; while mechanically robust, complex European electronics can be a source of issues if not maintained. Critical to adhere to maintenance schedules, especially for the timing belt.
