Why the 17c Formula Is Antiquated Garbage

If you’ve recently been in an accident and filed a diminished value (DV) claim, you may have been presented with a number based on the “17c formula.” Insurance companies love to lean on it because it produces the lowest possible payout. But here’s the truth: the 17c formula is deeply flawed, legally challenged, and has no real basis in actual market data.

The Origin of 17c

The 17c formula comes from a single Georgia court case (Mabry v. State Farm, 2001). The court allowed State Farm to use a formula to calculate diminished value, but it never endorsed it as the standard. In fact, the judge specifically stated the formula was only for that case. Despite this, insurers across the country adopted it—because it benefits them, not consumers.

Major Flaws in the Formula

1. Arbitrary “10% cap.”
   The formula assumes no vehicle can lose more than 10% of its value after an accident. Anyone who’s tried to sell a previously wrecked luxury SUV or performance car knows this is false. Market data shows losses can be 20%–30% or higher.
2. Unrealistic mileage adjustments.
   The formula applies a mileage deduction that slashes value further, even when mileage is average or irrelevant to the accident’s stigma.
3. No consideration of real-world comps.
   Buyers don’t consult formulas—they look at Carfax, Autocheck, and comparable vehicles. A repaired vehicle with accident history will sell for less, regardless of what 17c says.
4. One size fits all.
   A 2024 Tesla Model 3 and a 2010 Honda Civic are treated with the same flawed math. The formula doesn’t account for brand reputation, buyer perception, or market demand.

Courts and Regulators Agree

Many state insurance departments and courts have criticized or outright rejected the 17c formula. It’s not an accepted appraisal method, nor is it recognized by professional valuation standards like USPAP (Uniform Standards of Professional Appraisal Practice).

What You Actually Need: Market-Based Appraisals

At Premier Diminished Value Specialists, we don’t rely on arbitrary caps or formulas from 20 years ago. Our reports use:

• VIN-specific market comparables to show what your car is worth today.
• Accurate valuation methods aligned with real buyer behavior.
• Professional, detailed documentation that can hold up against insurance pushback.

Bottom Line

The 17c formula was never meant to be a national standard. It’s outdated, biased in favor of insurers, and doesn’t reflect what really happens when you try to sell your car. Don’t settle for a cookie-cutter calculation—demand a proper diminished value appraisal backed by real data.

👉 Need help with your diminished value claim? Contact us at Premier Diminished Value Specialists and get a no-risk, full-service DV report that’s tailored to your vehicle and situation.