Trip Meter

[mey0r]

How accurate is the tripmeter FC consumption system provided on those cars that have these? Will the output still accurate once you reset?

[1D4LV]

yes bro, i think so... this is controlled by the ECU.

[oj88]

A few factors will affect accuracy.

1. Mechanical speedometers (using a speedo cable) introduces the most errors and usually becomes better or worse in time as the the mechanical parts wear down due to friction. Most modern cars solved this by no longer using mechanical cables, but instead, utilized a speed sensor which counts the rotation of the shaft (typically) going to the tires.

2. Using different tire and rim sizes can also affect the disparity between the speedo's readout and your actual speed. This is self-explanatory I hope.

3. On the darker side of things, conspiracy theorists believe that some car manufacturers calibrates their speedo/odometers about 4-10% faster than the car's actual speed. This causes your warranty to run out a bit faster (if you're a hi-miler). For example, if your car is covered by a 3 yr/ 30,000Km warranty, even if your car's actual traveled distance is just 28,000 km, your odometer would've registered 30,800 km already (assuming a 10% error), which would technically put your car out of warranty.

You can check your speedo's accuracy by comparing it with the speed readout from a GPS. GPSes have tighter tolerances (typically 0.05 meter/sec or 0.18 km/hr), given that it should have a very good visibility of the sky. This method can show you how far off your speedo is in +/-n%

To compute your FC, be sure to factor in "n" above in your computations.