True Mileage Unknown, often shortened to TMU, is a mileage legend some states put on a title or show in a title inquiry. Connecticut's DMV defines it this way: mileage was not submitted when the title was applied for, and it may also indicate some discrepancy in the odometer reading. Until you can match the paper title, the number on the dash, and a history report you ordered yourself, treat that dash reading as unverified.
What True Mileage Unknown actually says
States do not all print the same words. Connecticut lists TMU among its branded-title legends and ties it to missing mileage at the time of the title application, with a possible odometer discrepancy thrown in. That is a record-keeping warning, and it is enough to change how you price the car. Other states may use different phrases for a similar problem, or they may print Not Actual Mileage and never say "True Mileage Unknown" at all.
The National Motor Vehicle Title Information System is the federal title-and-brand database states check against each other. The consumer explainer at vehiclehistory.gov says brands are descriptive labels that titling agencies apply, such as junk, salvage, and flood, and that NMVTIS keeps a history of brands applied by any state. It also says odometer fraud can leave you paying more than fair market value or buying an unsafe vehicle. Look, that page does not publish a glossary entry titled "True Mileage Unknown," so I am not going to pretend TMU is a numbered NMVTIS code I found there.
The American Association of Motor Vehicle Administrators publishes the numbered list states map into NMVTIS. The odometer codes include 68 for Actual, 69 for Not Actual, 71 for Exempt from disclosure, 72 for Exceeds Mechanical Limits, 73 for Odometer may be Altered, and 76 for Odometer Discrepancy based on earlier recorded values. If a report shows one of those codes next to a TMU stamp on the paper title, read both. Our explainer on NMVTIS brand codes helps when the report dumps a number without plain English.
How TMU sits next to NAM, exceeds mechanical limits, and exempt
Connecticut prints more than one mileage legend, and the wording is not interchangeable. "Not actual mileage" is listed as the case when a vehicle odometer reading cannot be determined. "Warning odometer discrepancy" means the odometer does not reflect the actual mileage. "Odometer exceeds mechanical limits" means the odometer started at zero again. TMU sits in that same list with its own sentence about mileage that was not submitted. If a seller says the labels are all the same, ask them to read the title out loud.
Virginia's DMV uses a cleaner four-way split. Actual means the displayed distance is the exact distance traveled. Not Actual means the exact distance is unknown, the reading should not be relied on, the brand is permanent, and recording it lowers the vehicle's value. Exceeds the Mechanical Limits covers older five-digit odometers that roll from 99999 back to zero. Exempt covers non-passenger cargo vehicles with a GVWR over 16,000 pounds, and Virginia will honor an exemption a prior state already indicated. If you are staring at an older or heavy vehicle, read our note on odometer-exempt vehicles instead of assuming a blank mileage box is TMU.
CARFAX's glossary defines a Not Actual Mileage title as the seller certifying, under the Federal Odometer Act, that the reading does not reflect actual mileage, which may happen because the odometer was tampered with, broken, or replaced. It defines Exceeds Mechanical Limits as a five-digit odometer that cannot track mileage after 99,999 miles, which we cover in how Exceeds Mechanical Limits shows up on a CARFAX report. I did not find TMU defined on that glossary page.
Oregon shows how a state can flag bad mileage without using the TMU label. Oregon DMV says you note "not readable" if a digital display is blank, and you give the reading and note "not actual" if the odometer is stuck. Those brands cannot be removed from the title. Oregon also skips disclosure for model years 2010 or older and for vehicles with a manufacturer's GVWR over 16,000 pounds.
NHTSA's odometer-fraud page is the federal backdrop. A written disclosure of the mileage on the title has to go from seller to buyer when ownership transfers, and if the mileage is incorrect the law requires a statement to that effect on the title. A vehicle is exempt from those written disclosure requirements if it is 20 years old or older, or a model year 2010 vehicle or older. The odometer disclosure statement rules walk through what the seller is supposed to sign.
Why the brand follows the car, and what to check
Virginia is blunt: a Not Actual brand is permanent and lowers value. Oregon is blunt in a different way: not readable and not actual stay on the title. I did not find a Connecticut sentence that says TMU can be scrubbed later, and I am not going to invent one. If you buy a TMU car hoping a clerk will fix it after the sale, you may be stuck explaining the brand to the next buyer, a lender, or an insurer who prices unknown miles carefully, or not at all.
We've seen seller-supplied PDFs that look like a clean mileage history while the paper title sitting on the hood carries a True Mileage Unknown or Not Actual stamp. Sometimes the PDF is cropped so the brand line never appears. Sometimes the screenshot is from a different VIN. Pull your own report on the number you read off the dash, then hold it next to the title. If the two documents tell different stories, believe the worse one until someone can prove otherwise.
NHTSA's buyer tips are still the right order. Ask to see the title and compare its mileage with the odometer, and examine the title closely if the mileage notation looks obscured. Compare the dash to maintenance records and pedal wear. Request a vehicle history report, and if the seller will not provide one, order it yourself with the VIN. If the readings bounce around, use our walkthrough on how to detect an odometer rollback. Honestly, you should not pay a low-mile price for unknown miles. Ask when the brand was applied. A real answer has a date and a document.
If you want a report through us, we are a licensed reseller of CARFAX and AutoCheck reports. We have no corporate tie to those brands or to Experian, and we do not hand out full official reports for free. Buying a single report direct from the brands has usually landed around $39.99 to $44.99. A guest checkout here has sat around $5.50. Confirm at checkout, because the figure in the cart is the one that matters. As of November 2026, the pages I quoted still describe TMU, NAM, Exceeds, and the federal disclosure rules the way they appear above. Other states word the same problem differently, so read the title in front of you.
If the title, the dash, and the report cannot be reconciled, walk or price the car as unknown miles. Hoping the next transfer will quietly drop TMU is not a plan.
Sources
- Connecticut DMV: branded title legends, including True mileage unknown
- Virginia DMV: odometer brands (Actual, Not Actual, Exceeds, Exempt)
- AAMVA: NMVTIS brand code values, including odometer brands 68 through 76
- NMVTIS / vehiclehistory.gov: what a vehicle history report includes
- NHTSA: odometer fraud, disclosure rules, and buyer checks
- Oregon DMV: not readable and not actual brands, plus disclosure exemptions
- CARFAX glossary: Not Actual Mileage and Exceeds Mechanical Limits
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