OBD2 Speedometer

[Stewart J]

Spending 6 months of the year in France/Spain and the very tight tolerances on being a km or two over the limit with the current generation of new speed cameras I am looking for an accurate speed indication. I have been using an old iPhone with various speedometer apps but results leave a lot to be desired. I recall posts about OBD speedos but cannot find them. Anyone any recommendations, and no soap boxers lecturing me on breaking speed limits I do not do it and 50 years of motoring have not had a speeding fine the current Ducato speedo is a joke when it comes to being able to read Kim’s so a nice large digital display is what I am looking for. Many thanks in advance, there are many to choose from on fleabay but users reviews/recommedations I would appreciate.

 

[Macca1954]

Spending 6 months of the year in France/Spain and the very tight tolerances on being a km or two over the limit with the current generation of new speed cameras I am looking for an accurate speed indication. I have been using an old iPhone with various speedometer apps but results leave a lot to be desired. I recall posts about OBD speedos but cannot find them. Anyone any recommendations, and no soap boxers lecturing me on breaking speed limits I do not do it and 50 years of motoring have not had a speeding fine the current Ducato speedo is a joke when it comes to being able to read Kim’s so a nice large digital display is what I am looking for. Many thanks in advance, there are many to choose from on fleabay but users reviews/recommedations I would appreciate.

Use the one on my garmin sat nav surely that must give a correct enough speed reading. No tickets yet I must add ?

 

[Ingwe]

Use the one on my garmin sat nav surely that must give a correct enough speed reading. No tickets yet I must add ?

Same for us. And the Garmin gives an audio warning if you break the limit so you can slow down immediately.

 

[bigalw35]

Get in touch with Jon Pullarra (I think he,s son’s name is Jamey) Digital-speedos.co.uk he covers a wide range of electronic speedos, initially for motor bikes, but now more for sports cars, mention my nickname (bigal) you may get a discount, I know him very well, good luck ?

 

[Stealaway]

TomTom satnav for me too and always set to KPH in Europe. Audible warnings are a life / money saver.

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[pappajohn]

Sat nav speed. I may be wrong but I'm sure I'm not.
On a flat road the nav speed will read 50mph.
Decend a steep hill and the nav speed remains at 50mph but your actual road speed is higher.

The sat sees the nav on a level plane and calculates speed from that.
Going down (or up) hill it would show as slower as your forward speed (in the level plane) has reduced so you increase speed to maintain 50mph in the level plane.
In other words you may have descended 1000mtrs but only travelled forwards (in the level plane) 750mtr.

 

[joka250]

Sat nav speed. I may be wrong but I'm sure I'm not.
On a flat road the nav speed will read 50mph.
Decend a steep hill and the nav speed remains at 50mph but your actual road speed is higher.

The sat sees the nav on a level plane and calculates speed from that.
Going down (or up) hill it would show as slower as your forward speed (in the level plane) has reduced so you increase speed to maintain 50mph in the level plane.
In other words you may have descended 1000mtrs but only travelled forwards (in the level plane) 750mtr.

You are correct I believe, terrain affects accuracy of GPS . For easy viewing an HID device is well regarded by many although I like others rely on my sat nav.

 

[StephDeLux]

The ODB2 will give you the exact same information as the speedometer on your dashboard. If you want a more precise indication, use a precise GPS like a Garmin.

 

[Millcourt]

As well as using a SatNav or an App on a mobile phone to display GPS derived speed readings, you can also use a suitable Dashcam.

You may find it worth having a look at an earlier thread I started on this at..........

Easier to read Speed

Many have previously said how difficult it can be to read the speed on the dash speedometer fitted on the Fiat/Peugeot cabs and I have found this to be the case - especially when driving in bright sunlight and also when trying to decipher the speed in kph when abroad. Our TomTom SatNav does of...

www.motorhomefun.co.uk

In the new Series 2 Nextbase dashcams I understand all models can be set to display speed in either MPH or KPH. In the previous Series 1 models only the models 512GW and above have this function.

 

[Steve N Tracy]

I use one of these, it's not head's up at all you read directly off the lcd screen, can be set easily to mph or kmh, also reads 2 other functions at the same time, ie rpm and voltage, and reads of odb fault codes.

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[Deneb]

Sat nav speed. I may be wrong but I'm sure I'm not.
On a flat road the nav speed will read 50mph.
Decend a steep hill and the nav speed remains at 50mph but your actual road speed is higher.

The sat sees the nav on a level plane and calculates speed from that.
Going down (or up) hill it would show as slower as your forward speed (in the level plane) has reduced so you increase speed to maintain 50mph in the level plane.
In other words you may have descended 1000mtrs but only travelled forwards (in the level plane) 750mtr.

You're right but the error in almost all cases will be less than the speedometer error. A larger concern (as someone on another forum has found to their cost) is that it can be risky to rely on GPS signals being 100% accurate at all times. Knowing the difference between the speed indicated by my satnav and the speedometer on my van, I have noticed on a few occasions that the satnav indicated speed has deviated from the normal difference, and on one occasion was about 8 mph slower then the speedometer for several miles when travelling along the M4. If I hadn't been aware of that and was using the satnav to maintain my speed, I would have been travelling about 6mph faster than my true speed.

It happens very rarely in my experience, but sods law dictates that it may happen in the worst possible circumstances.

I won't mention that time that my speedometer failed by gradually reading slower and slower over several days until it stopped altogether. I wondered why the nice Norwegian policeman was waving at me when (I thought) I was travelling well within the speed limit through the Laerdal tunnel They had set up a speed check in the large antechamber about half the way through!

 

[Ridgeway]

The ODB2 will give you the exact same information as the speedometer on your dashboard. If you want a more precise indication, use a precise GPS like a Garmin.

but in KMH and not MPH, i assume that was the request

 

[Ridgeway]

OBD2 apps are certainly accurate enough and all the boys and girls into hot hatch tuning use them with a phone based app, often used for standing 1/4 mile stats and 0-60mph etc. Now lets see your 1/4 mile in the van

 

[ctc]

I use UK limits all slightly slower than the French ones but the rules are near enough the same.

 

[StephDeLux]

but in KMH and not MPH, i assume that was the request

Right. I missed that. Sorry.

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