Service History: Why Documentation Matters When Buying Used Cars

The Importance of Service History

When buying a premium used car from BMW, Mercedes, or Audi, the service history is often more important than the mileage. Complete documentation can make the difference between a good purchase and an expensive mistake. This guide explains what to look for.

Why Documentation Matters So Much

Price Impact by Documentation Level

Documentation	Price Effect	Sellability
Complete with invoices	+15-25%	Very high
Maintained service book	+5-15%	High
Partially documented	Baseline	Medium
No documentation	-20-35%	Difficult

Concrete Examples from Our Database

BMW E38 740i:

• With complete history: €19,500
• Without documentation: €14,200
• Difference: €5,300 (37%)

Mercedes W140 S500:

• With complete history: €16,800
• Without documentation: €11,900
• Difference: €4,900 (41%)

Audi D2 A8 4.2:

• With complete history: €12,400
• Without documentation: €8,200
• Difference: €4,200 (51%)

What Good Service History Includes

Essential Documents

1. Service Book

   • All maintenance with date and mileage
   • Workshop stamp
   • Service technician signature

2. Invoices and Receipts

   • Detailed work listing
   • Parts used with part numbers
   • Labor time and hourly rate

3. Inspection Reports

   • All safety inspections
   • Listed defects and their repair
   • Mileage progression

4. Additional Documents

   • Tire change protocols
   • Air conditioning service
   • Software updates

Evaluation Checklist for Buyers

Document	Present	Complete	Plausible
Service book	[ ]	[ ]	[ ]
Invoices 5 years	[ ]	[ ]	[ ]
Inspection reports	[ ]	[ ]	[ ]
Timing belt/chain	[ ]	[ ]	[ ]
Transmission service	[ ]	[ ]	[ ]
Brake replacement	[ ]	[ ]	[ ]

Critical Maintenance Intervals by Model

BMW E38/E39/E46

Maintenance	Interval	Cost if Neglected
Complete cooling system	80,000 km	€1,500-3,000
VANOS seals	120,000 km	€800-2,500
Automatic transmission fluid	60,000 km	€2,000-5,000
Differential oil	100,000 km	€300-800
Brake fluid	2 years	€50-150

Mercedes W140/W210

Maintenance	Interval	Cost if Neglected
Timing chain (M104/M119)	150,000 km	€2,000-4,000
ABC system (if equipped)	60,000 km	€3,000-8,000
Automatic transmission	60,000 km	€2,500-6,000
AC compressor	120,000 km	€800-1,500
Steering gear	150,000 km	€1,200-2,500

Audi D2 A8

Maintenance	Interval	Cost if Neglected
Timing belt (V8)	120,000 km	€1,500-2,500
Quattro transfer case	80,000 km	€1,000-2,000
Air suspension	100,000 km	€2,000-5,000
Multitronic (if equipped)	60,000 km	€3,000-7,000

Warning Signs in Documentation

Red Flags

1. Gaps in History

   • Missing years without explanation
   • Sudden workshop changes
   • Implausible mileage readings

2. Unrealistic Claims

   • Too low maintenance costs
   • Missing wear parts
   • No major repairs despite high mileage

3. Suspicious Patterns

   • Always same, low invoice amount
   • Missing part numbers
   • Illegible or missing stamps

Plausibility Check

Minimum Annual Costs for Premium Vehicles:

Vehicle Class	Minimum/Year	Realistic/Year
BMW 3/5 Series	€600	€1,200-2,000
BMW 7 Series	€800	€1,500-3,000
Mercedes E-Class	€700	€1,200-2,200
Mercedes S-Class	€900	€1,800-3,500
Audi A6/A8	€750	€1,400-2,800

Using Digital Documentation

Modern Options

1. Manufacturer Databases

   • BMW: Query possible through dealers
   • Mercedes: Service history via Mercedes me
   • Audi: myAudi service history

2. Independent Sources

   • TecDoc for part numbers
   • Carfax/AutoDNA for accident history
   • Local vehicle history reports

Invoice Verification

• Call workshop phone number
• Compare part numbers with catalog
• Check labor times for plausibility

Recommendations for Buyers

Before Purchase

1. Request All Documents

   • Minimum: Service book + last 3 invoices
   • Ideal: Complete folder since first registration

2. Verify the Information

   • Contact workshop
   • Check mileage progression
   • Analyze time intervals

3. Evaluate Quality

   • Authorized dealer vs. independent shop
   • OEM parts vs. aftermarket
   • Documented vs. assumed maintenance

After Purchase

1. Continue Documentation

   • Create own folder
   • Keep all invoices
   • Take photos of work done

2. Digital Backup

   • Scans of all documents
   • Cloud backup
   • Mileage log

Conclusion

A complete service history is worth real money for premium used cars. It provides certainty about the vehicle’s condition, protects against hidden defects, and secures resale value. Invest time in reviewing documentation - it’s one of the most important decisions when buying a used car.

Rule of Thumb: A well-documented vehicle at a higher price is often the better choice than an undocumented bargain.

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This guide is based on our analysis of over 2,500 vehicles in the German premium used car market. As of: May 2025