skills/used-car-investigator/references/scoring.md

# Scoring and Verdict Method

## Category weights

Score each category from 0 to its maximum:

- Engine reliability and risk: 15
- Transmission/drivetrain reliability and risk: 15
- Mileage + maintenance outlook: 15
- Accident/title/history: 12
- Condition + evidence quality: 8
- Repairability + repair costs: 10
- Value for money: 10
- Driving dynamics: 10
- Fuel/operating efficiency: 5

Total before penalties: 100.

## Category anchors

### Engine / propulsion system — 15
For a BEV, score the electric drive unit, inverter, and high-voltage propulsion system here; do not
pretend a nonexistent combustion engine is being assessed. For a hybrid or plug-in hybrid, include both
the combustion engine and electric propulsion components.

For an electrified vehicle, assign the separate battery-health and evidence grades from
`battery-health.md`, then reflect them here and in maintenance, repairability, value, and confidence as
appropriate. Do not award healthy-battery points merely because no warning light is present, and do not
double-penalize the same risk.

15 = strong engine reputation, no material unresolved pattern, evidence supports maintenance.
10-12 = generally good with manageable known issues.
6-9 = meaningful recurring expensive issue or weak history.
0-5 = severe unresolved catastrophic risk, active symptoms, or evidence of major failure.

### Transmission/drivetrain — 15
Use the same severity logic. Complex DCT/CVT/AWD systems with expensive unresolved risks should not score like conventional robust units merely because they currently drive normally.

### Mileage + maintenance — 15
15 = major mileage services documented, little near-term catch-up.
10-12 = normal wear/costs for age.
6-9 = several undocumented/approaching expensive services.
0-5 = major overdue work or mileage places multiple expensive systems at risk.

### Accident/title/history — 12
12 = well-documented clean history with no material contradictions.
8-10 = minor repaired incident with credible documentation.
4-7 = meaningful accident, gaps, or ambiguous history.
0-3 = structural concern, branded title with poor documentation, odometer inconsistency, flood concern, or material contradiction.

### Condition + evidence — 8
Reward records and observable condition, not seller confidence. Include tire tread, age, matching, wear,
and evidence quality; do not award full condition points when tire replacement is unknown or imminent.

### Repairability — 10
10 = broad mechanic familiarity, accessible service, affordable/common parts.
5 = specialist dependence or expensive labour.
0-3 = scarce parts/service, proprietary complexity, exceptionally costly routine repairs.

### Value — 10
Compare true purchase cost against local comps and risk-adjusted fair value. Include a matched tire set,
mounting/alignment, mandatory dealer fees, and other deterministic transaction costs when applicable.

### Driving — 10
Assess steering, ride, handling, braking, powertrain response, acceleration, engagement, ergonomics, and
practical fit. Cargo capacity is a buyer-fit modifier, not generic reliability points; show seats-up and
seats-folded capacity and let the buyer's stated use affect the recommendation.

Dealership experience is reported separately as Low concern / Mixed / High concern. It is not a substitute
for vehicle evidence or an automatic score deduction, but hidden fees, refusal of a reasonable PPI, or
materially misleading terms can trigger a value adjustment or a hard walk-away condition.

### Fuel/energy — 5
Consider consumption, fuel grade/type, charging cost and access, battery degradation, and winter efficiency.
Do not punish premium fuel or high charging demand heavily when the vehicle's segment/performance makes it
expected; score relative to realistic alternatives.

## Catastrophic-risk penalties

Apply AFTER category scoring when warranted:

- unresolved credible $5k-$9,999 potential failure: -3 to -8
- unresolved credible $10k+ potential failure: -6 to -15
- active symptoms of catastrophic engine/transmission failure: -10 to -25
- structural/flood/odometer deception concern: -10 to -30
- seller materially misrepresented verifiable history: -5 to -20

Do not double-penalize the exact same fact excessively. Explain the penalty.

## Confidence

High: exact powertrain resolved, strong source coverage, VIN/history evidence, good maintenance documentation.

Medium: major technical facts resolved but some history/service evidence missing.

Low: VIN absent, powertrain ambiguous, listing inaccessible, or critical maintenance/title facts unverified.

## Verdict bands

These are guides, not automatic outputs:

- 88-100: STRONG BUY, if no unresolved red-flag gate
- 78-87: BUY
- 68-77: BUY IF PPI PASSES or NEGOTIATE
- 55-67: NEGOTIATE or HIGH-RISK BUY
- below 55: usually AVOID

Override the numeric band downward for:

- credible structural/flood/odometer concern
- active major engine/transmission symptoms
- unresolved title/ownership problem
- seller deception
- price that fails to compensate for catastrophic-risk exposure

## Maximum recommended purchase price

Start with evidence-supported local fair value for a clean, properly maintained comparable example.

Subtract:

- immediate required repairs
- overdue/undocumented maintenance where catch-up is prudent
- near-term unavoidable wear items
- accident/title discount
- modification discount where warranted
- risk premium for unresolved high-cost known issues

Do not subtract every possible future failure at full cost. Separate risk premium from deterministic work.