My speedometer drops past 70 when I'm only going about 35 mph trying to figure out what is about to go wrong before I'm caught off guard.
My car has 179569 miles.
My car has an automatic transmission.
Hi - this behavior sounds like a failed speedometer instrument (the portion in the dash cluster rather than the cable from the transmission). It will be necessary to remove the speedometer "gauge", and either have it repaired at a speedometer instrument repair facility, or replaced with a new unit. Remember, if you replace it, and the odometer mileage displayed is different that your current reading, that must be reported as different when you sell the vehicle. I recommend a speedometer inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, confirm this diagnosis, and give you an accurate assessment of damage and cost estimate for repairs.
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