# Speedo error on continental flying spur



## bentleysucks (Aug 16, 2011)

The speedo on my Flying Spur reads about 7% high. Bentley Motors calls this error a "design feature" and says it cannot be changed (they do not like the word FIXED, as they opine it is supposed to do that). Have any of you had any success in properly calibrating the speedo to one's actual speed? Thank you.


----------



## Paximus (Aug 26, 2011)

At the risk of being boring, here's the answer to speedometer errors. It is government policy to make vehicle manufactorers calibrate speedos such that they must never read low. In other words, it can never be a legal defense to a speeding charge to say the speedo said it was OK.

The Flying Spur uses similar systems to the Phaeton, and in North America this reads 7% high, which is the sum of all possible errors that could make it read low. Such as having new tyres (larger diameter), very high tyre pressures (these can be set high in North America specs to increase ground clearance compared to European specs), owner puts on over-size tyres (ditto), calibration error in the electronics (small but possible), air temperature difference, etc.

There are controller adaptation settings that can be done at the dealership to tell the system larger diameter tyres are fitted, which corrects the odometer, but the speedo offset against the odometer's calculated speed is usually preset. You can check this offset by driving at a steady speed for a mile or so, then compare the speedo with the average speed calculated by the controllers on the trip display. This is usually deadly accurate if the tyre sizes, wear and pressures are as expected, being used for the traction systems such as ABS etc.

This 2-page article reveals the reasons for Europe, and similar rules are used for North America.


Chris


----------



## bentleysucks (Aug 16, 2011)

Hi Chris. Intelligent is never boring. Frankly, yours is the best reasoned response I've seen. The problem is, Bentley Motors has stated it is NOT POSSIBLE to recalibrate my speedo. While your answer makes more sense, that's their position. I dont expect it to be perfect perfect perfect, but they could surely get it to within 1% or so. We did drive at a steady state with a GPS to assess the error. That an error exists at some point is, as you note, for a reason, even if a bad one. That they WONT (as opposed to CANT) correct it to some extent is one more reason not to purchase any product from Bentley Motors.


----------



## Paximus (Aug 26, 2011)

It's a shame that you can't get what you want. I thought that such a premium manufacturer was intent on delivering anything the Customer wanted, if they could feasibly do it.

Maybe it would cost $$$ to work on the controller software, possible under subcontract to a third-party company. The existence of non-standard code would block any future updates using the dealer automated help system, and perhaps invalidate their type approval certificate for your vehicle.

There's also the $$$ for the lawyers' costs in drawing up the disclaimers! But I won't go there.

Must be very frustrating.

Chris


----------



## bentleysucks (Aug 16, 2011)

Currently, the car has a year of extended warranty remaining. If I do anything unauthorized to the car, they'll likely disclaim warranty coverage if anything goes awry. Cant blame them for that. Too, even if the car was out of warranty, we'd be scared to mes with the computer, as a repair would be $$$$$. From what we're told, many customers have complained of inaccurate speedos. You'd THINK Bentley Motors would care enough to do SOMETHING. I asked them to have Mulliner make me a GPS bracket for my dash as compensation, so the Garmin wouldnt go flying all over the place when pushing the fast or slow pedal hard. They immediately declined. Never have we encountered such a hateful manufacturer. Amazing.


----------



## deagle (Feb 22, 2011)

is the speedo hand-made or computer-made ?

either way, the car should be close to perfect

get a Rolls next time, lol


----------



## bentleysucks (Aug 16, 2011)

The speedo, though analog, is computer controlled, and Bentley Motors told me the "error" is not an error, but rather a "design feature" to keep people from going faster than they think they're going, and that adjustment is not possible. 





deagle said:


> is the speedo hand-made or computer-made ?
> 
> either way, the car should be close to perfect
> 
> get a Rolls next time, lol


----------



## PanEuropean (Nov 3, 2001)

bentleysucks said:


> ...Bentley Motors told me the "error" is not an error... and that adjustment is not possible.


They told you the truth.

If you refer to the Car and Driver article that Chris (Paximus) linked to earlier in this discussion, you will see that the automobile manufacturer has no choice in the matter at all. Regardless of whether they build to the SAE spec or the EC spec (your car will conform to the SAE spec, because you bought it in the USA), the speedometer is going to read high because that's what the industry spec calls for. Every standard production automobile that is sold in North America is similar.

Michael
Phaeton Forum Moderator


----------



## bentleysucks (Aug 16, 2011)

Hi Michael. Actually, that's not at all true. While they may not read LOW, my MB was dead-on, my Chevy is dead-on, my Cadillac is, maybe, around 1% or less high, and most of the other cars I've driven are in the dead-on to 1-2% high range. 6-7% high, on factory tires/wheels, is inexcusable. A tiny increment...perhaps.....but 7%...noooo. 
Too, just what industry spec is it that calls for a speedo to read grossly high? 
I drove a new RR Ghost this summer, and even that car was closer to dead-on than high.
So, what gives with our car?



PanEuropean said:


> They told you the truth.
> 
> If you refer to the Car and Driver article that Chris (Paximus) linked to earlier in this discussion, you will see that the automobile manufacturer has no choice in the matter at all. Regardless of whether they build to the SAE spec or the EC spec (your car will conform to the SAE spec, because you bought it in the USA), the speedometer is going to read high because that's what the industry spec calls for. Every standard production automobile that is sold in North America is similar.
> 
> ...


----------

