The Perfect Test Drive: Systematic Approach to a Safe Purchase
A thorough test drive is the most important step when buying a used car. This checklist helps you identify hidden defects and make informed decisions.
Before the Test Drive
Visual Inspection (10 Minutes)
| Checkpoint | What to Look For | Rating |
|---|
| Paint Condition | Color differences, respray | [ ] OK [ ] Issue |
| Panel Gaps | Even at doors, hoods | [ ] OK [ ] Issue |
| Glass | Cracks, stone chips | [ ] OK [ ] Issue |
| Tires | Tread depth, even wear | [ ] OK [ ] Issue |
| Underbody | Rust, leaks | [ ] OK [ ] Issue |
Engine Bay Check
| Component | Inspection | Status |
|---|
| Oil Level | Between Min/Max, color | [ ] OK [ ] Issue |
| Coolant | Level, color (not rusty) | [ ] OK [ ] Issue |
| Brake Fluid | Level, age | [ ] OK [ ] Issue |
| Belts/Chains | Condition, tension | [ ] OK [ ] Issue |
| Hoses | Cracks, porosity | [ ] OK [ ] Issue |
The Cold Start Test
Why Cold Start Matters
Cold start reveals many hidden problems. Insist on starting the vehicle with a cold engine.
Cold Start Checklist
| Observation | Possible Problem | Severity |
|---|
| Starter turns slowly | Battery, starter | Medium |
| Hard starting | Injection, ignition | High |
| Rattling on start | Timing chain, tensioner | Critical |
| Blue smoke | Oil consumption, valve seals | High |
| White smoke | Head gasket, coolant | Critical |
| Rough idle | Ignition, injection | Medium |
BMW-Specific
| Problem | Common in | Meaning |
|---|
| VANOS rattle | M52, M54, N52 | VANOS actuators |
| High idle when cold | M54, N52 | Idle controller |
| Ticking noises | N20, N55 | Timing chain |
Mercedes-Specific
| Problem | Common in | Meaning |
|---|
| Diesel clatter (petrol) | M271 | Chain tensioner |
| Hissing | M112, M113 | Intake manifold gasket |
| Vibrations | OM646, OM651 | Injectors, dual-mass |
Audi-Specific
| Problem | Common in | Meaning |
|---|
| Chain rattle | 2.0 TFSI (EA888) | Timing chain |
| Clicking | 1.8T | Lifters, camshaft |
| Whistling | 2.7/3.0 TDI | Turbo, EGR |
The Test Drive Route
Ideal Route Composition
| Route Type | Duration | Purpose |
|---|
| City traffic | 10 min | Stop-and-go, clutch, automatic |
| Country roads | 15 min | Normal driving, transmission |
| Highway | 10 min | High speed, stability |
| Hilly terrain | 5 min | Power under load |
Minimum duration: 30-40 minutes
During the Drive
Engine and Drivetrain
| Checkpoint | Test | Expectation |
|---|
| Acceleration | Full throttle from low RPM | Strong, no hesitation |
| Shift behavior | Shift through all gears | Precise, quiet |
| Kickdown (automatic) | Full throttle at 50 km/h | Quick downshift |
| Clutch (manual) | Hill start | No slipping |
| Hot idle | After warm-up | Stable, no vibrations |
Suspension and Steering
| Test | Method | Warning Signs |
|---|
| Straight-line tracking | Release steering briefly | Pulls to one side |
| Steering precision | Slalom movements | Imprecise, play |
| Suspension | Over bumps | Clunking, bottoming out |
| Brakes | Normal braking | Vibrations, squealing |
| Emergency braking | ABS test (safely!) | Uneven, long |
Identifying Noises
| Noise | Possible Cause | Action Required |
|---|
| Whistling with RPM | Turbo, belts | Medium |
| Rhythmic clicking | Valves, lifters | Low-Medium |
| Rattling on throttle change | Driveshaft, differential | High |
| Speed-dependent humming | Wheel bearing | Medium |
| Clunking over bumps | Suspension, bushings | Medium-High |
| Metallic grinding | Brakes, wheel bearing | High |
Electronics Check
Interior Test
| System | Test | Status |
|---|
| Air conditioning | Cooling and heating | [ ] OK [ ] Issue |
| Seat adjustment | All directions (electric) | [ ] OK [ ] Issue |
| Window lifters | All windows, sunroof | [ ] OK [ ] Issue |
| Infotainment | Radio, CD, navigation | [ ] OK [ ] Issue |
| Instruments | All displays, warning lights | [ ] OK [ ] Issue |
Driver Assistance
| System | Test | Status |
|---|
| ABS | Braking on gravel | [ ] OK [ ] Issue |
| ESP | Can be deactivated? | [ ] OK [ ] Issue |
| Cruise control | Set, hold, cancel | [ ] OK [ ] Issue |
| PDC | Front and rear | [ ] OK [ ] Issue |
| Xenon/LED | Height adjustment, dipping | [ ] OK [ ] Issue |
After the Test Drive
Hot Engine Check
| Checkpoint | Normal | Warning Sign |
|---|
| Coolant temperature | 85-95C | Over 100C |
| Idle RPM | 600-800 | Fluctuating |
| Oil pressure light | Off | On or flickering |
| Exhaust smell | Neutral | Sweet, burning |
| Underbody check | Dry | New spots |
Fault Code Reading
OBD2 diagnosis is essential:
| Error Type | Meaning | Recommendation |
|---|
| No errors | Good, or cleared | Check historical errors |
| Sporadic errors | Occasional problems | Clarify cause |
| Active errors | Current problem | Negotiation basis |
| Cleared errors | Possible cover-up | Caution |
Model-Specific Checkpoints
BMW
| Model | Especially Check |
|---|
| E46/E39 | Cooling system, VANOS, rear bushings |
| E60/E90 | Timing chain, electronics, turbo |
| E38 | Self-leveling, climate control |
Mercedes
| Model | Especially Check |
|---|
| W210 | Rust, automatic transmission, SBC |
| W203 | Steering rack, supercharger, rust |
| W140 | Air suspension, A/C, electrics |
Audi
| Model | Especially Check |
|---|
| B5/B6 | Turbo, timing case, Quattro |
| C5 | Air suspension, automatic, Multitronic |
| 8N TT | Haldex, water pump, turbo |
Negotiation Strategy After Test Drive
Document Defects
| Defect Found | Estimated Cost | Negotiation |
|---|
| Timing chain | 1,500-3,000 EUR | Deduct fully |
| Complete brakes | 800-1,500 EUR | Deduct 70% |
| Minor issues | < 500 EUR | Deduct 50% |
| Cosmetic/wear | varies | Individual |
Documentation
- Note all irregularities
- Photograph defects
- Ask to see service book
- Request inspection protocol
Conclusion: The Golden Rules
- Always cold start: Insist on cold engine
- Long test drive: At least 30 minutes
- Various routes: City, country, highway
- Check systematically: Work through checklist
- Diagnostic check: OBD2 reading is mandatory
- Document: Note and photograph everything
All data based on our continuous market analysis. As of: May 13, 2024