Speedo Error

[Blue850r]

Hi Guys,

 

How much Speedo error do you experienced in your car? Say speedo indicate top speed 220km/h but GPS only indicate 208km/h. Which car is more accurate and which make is the worst?

[Espire]

Hi Guys,

 

How much Speedo error do you experienced in your car? Say speedo indicate top speed 220km/h but GPS only indicate 208km/h. Which car is more accurate and which make is the worst?

 

 

I think speedo is more accurate than gps.

 

speedo error normally depends on the aftermarket size tyres u changed to... if u had stay to stock since day one.. ur speedo reading shouldnt be too far off from the actual speed...

 

gps have propagation delay in terms on tracking real-time speed.

[Hamburger]

my TIPO shows 4% diff. car runs 100 but tipo indicates 96. WHEN @200, TIBO show 192....so which is which

[macrosszero]

Most cars are actually reading 10% too fast on their speedometers.

 

 

[Kiadaw]

I never into speedo, actually, I am not even into swimming , but I heard Speedo Lzr Racer damn good. Michael Phelps won 8 golds with the suit.

 

Didn't know it could record & read speed. No wonder so expensive.

 

 

 

Ok, serious now,

 

My experience is that car usaually have slightly higher reading than actual, maybe as a safety factor. Afterall, its safe to have higher than lower reading should the reading be wrong. Example, say the instructment have an error tolarent of +/-5 mph/kph. Maybe they will set 5 mph lower than expected. So worst case, the speed the actual. So Manufactorer save the headache of people suing them when they got speeding tickets & such. It my pure speculation thou.

[Twofouronenite]

my TIPO shows 4% diff. car runs 100 but tipo indicates 96. WHEN @200, TIBO show 192....so which is which

Stock rims and tyres? If u have change them easier to calculate the diference.

 

[Hamburger]

Stock rims and tyres? If u have change them easier to calculate the diference.

oh yeah, as i upgraded my size 2" up, there is a diff of -0.71% from e stock

 

 

[Marcng]

my defi reads my top speed as 233km/hr but the speedo is already 240km/hr.....dunno which is more accurate....

[Thumbs]

I think speedo is more accurate than gps.

 

speedo error normally depends on the aftermarket size tyres u changed to... if u had stay to stock since day one.. ur speedo reading shouldnt be too far off from the actual speed...

 

gps have propagation delay in terms on tracking real-time speed.

Depends greatly on the kind of GPS receiver you're talking about and the sample rate, but most GPS receivers these days are definitely more accurate than speedometer readings.

 

GPS speed was compared to speedometer speed. The effect on speed accuracy of satellite number; changing satellite geometry, achieved through shielding the GPS antenna; speed; horizontal dilution of precision and cyclist position on a straight or a bend, was evaluated. The relative contribution of each variable to overall speed accuracy was determined by ANOVA. The speed determined by the GPS receiver was within 0.2 ms(-1) of the true speed measured for 45% of the values with a further 19% lying within 0.4 ms(-1) (n = 5060). The accuracy of speed determination was preserved even when the positional data were degraded due to poor satellite number or geometry. GPS data loggers are therefore accurate for the determination of speed over-ground in biomechanical and energetic studies performed on relatively straight courses.

 

http://www.ncbi.nlm.nih.gov/pubmed/15519597

[Blue850r]

Depends greatly on the kind of GPS receiver you're talking about and the sample rate, but most GPS receivers these days are definitely more accurate than speedometer readings.

 

GPS speed was compared to speedometer speed. The effect on speed accuracy of satellite number; changing satellite geometry, achieved through shielding the GPS antenna; speed; horizontal dilution of precision and cyclist position on a straight or a bend, was evaluated. The relative contribution of each variable to overall speed accuracy was determined by ANOVA. The speed determined by the GPS receiver was within 0.2 ms(-1) of the true speed measured for 45% of the values with a further 19% lying within 0.4 ms(-1) (n = 5060). The accuracy of speed determination was preserved even when the positional data were degraded due to poor satellite number or geometry. GPS data loggers are therefore accurate for the determination of speed over-ground in biomechanical and energetic studies performed on relatively straight courses.

 

http://www.ncbi.nlm.nih.gov/pubmed/15519597

Speedo should be optimistic just to keep us out of trouble with the law. But some cars have very high error.

[Sw20]

I'm using Holux... It states correctly.

[Beei]

Use my Holux in different cars before..

Always around 10 km/h lesser than on speedo..

So I guess my own car pretty accurate..

 

 

[Fazer]

anybody try using RSM?

[Cyberchip17]

Using Garmin nuvi 205W on Nissan Murano, stock tyres and wheels.. Speedometer 90kmh, GPS 82kmh. Roughly the same in Nissan Sylphy also... I guess these Nissan speedometers over-reading by about 10%. Cannot comment for other models like Latio, Teana, 350Z or GT-R!