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Old 8th July 2015, 17:17   #2026
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Default Re: Jetta owners - is your odo accurate?

Quote:
Originally Posted by tilt View Post
I first noticed that my new Jetta showed an increase of ten+ kms in the distance driven door-to-door Bangalore to Madras when compared to my old i20.

Then, two days ago, I decided to verify it. I used VW's own app to trace my route over a few rides and compare it with what the odo showed.

The app's GPS tracker showed 12.15 km and the odo showed 13.5; the app showed 10.91 and the odo showed 11.7; and the third trip the app showed 26.43 kms and the odo showed 28.3.

And as I mentioned in the beginning of this post, my BLR-MAA distance showed around 360 kms instead of the 343 shown by my i20.

I want to know if other Jetta owners have noticed something similar.

Some of the other T-BHPers I spoke with thought it might have to do with any tyre size changes, but I am running the original wheels and tyres the car came with.

Yes, I agree that the difference does not seem to be significant, but I am unable to find a steady pattern to the difference, and was wondering how I may have this corrected.

As to WHY I would like it corrected, it would show a higher usage of the car over time, and also the fuel-consumption figures would not be accurate; not to mention the speedo also being optimistic.

Thanks and cheers
Interesting problem.

The 17km error over 343km indicates that the Jetta has an error of +4.9%. There are many factors that contribute to the error.

1. We can say Jetta has a +4.9% error only if we know that the distance measured by i20 has 0% error. What if both i20 and Jetta have some error and the actual distance is something in between. For example, the actual distance could be 350km, which indicates a -2% error on i20 and +2.8% error on Jetta. It could also be worse - the actual distance is only 340km which will make i20 to have a +ve error and Jetta with a worse error.

2. Change in circumference of the tire due to tire wear. The car calculates the distance based on number of revolutions made by the wheel. As the tire wears, the diameter reduces and hence the circumference. So, for the same number of revolutions of the wheel, while the odo indicates a distance, the car would have traveled lesser distance. Below link has a calculation that indicates upto 2% error in distance measurement between a new and worn tire.

http://mechanics.stackexchange.com/q...eedometer-accu

So, the tire wear in i20 and Jetta would spread the error.

3. Change in circumference of the tire due to pressure difference. The rolling circumference of a tire with lesser pressure is smaller than a tire with higher pressure. I could not get a definite number for % change in circumference with respect to change in psi. As indirect TPMS systems (like the one in Octavia) are based on this principle, I am sure the change should be significant enough (may be 1%) for the system to detect. So, the comparison between i20 and Jetta could be affected by the tire pressures of the cars during these rides.

4. Difference in actual distance travelled by i20 and Jetta. It is practically not possible to have traveled the same path in both the trips. Between the two trips, there would be incremental changes in distance traveled due to lane changes, wide vs narrow cornering etc that could accmumulate over a long distance. Theoretically, these changes should average out, but still there will be some difference.

I would not consider VW app as a standard. The distance measurement on GPS depends on various factors. The absolute accuracy of the GPS on your phone, number of samples the app averages to calculate the route etc. Also, I doubt if VW app implements compensation for gradient of the route which itself could introduce a -ve error in the distance calculated by the app.

From all the above factors, the actual error on the Jetta may not be as bad as 4.9%. Even if you consider there is a 5% (just rounded off) error:

The odo would read 1,05,000km instead of 1,00,000km.
The speedo would show 105kph instead of 100kph.

As you rightly said, this is not very significant.

My suggestion: Have fun with the car instead of worrying about a 5% error on the speedo/odo

Just my 2 cents!
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Old 16th July 2015, 13:42   #2027
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Default Re: Volkswagen Jetta : Test Drive & Review

Firstly, my apologies for the delayed response - I was travelling and did not login to tBHP. Secondly, thank you, Graaja and VW2010 for responding.

Quote:
Originally Posted by VW2010 View Post
Could be a sensor issue or sensor calibration issue?

Did you check with VW.

Also any mods to the rims or tyres
I have not checked with VW yet, I shall wait until I get in for the 7500 km check-up. And there are no mods to the tyres or rims.

Quote:
Originally Posted by graaja View Post
Interesting problem.

The 17km error over 343km indicates that the Jetta has an error of +4.9%. There are many factors that contribute to the error.

1. We can say Jetta has a +4.9% error only if we know that the distance measured by i20 has 0% error. What if both i20 and Jetta have some error and the actual distance is something in between. For example, the actual distance could be 350km, which indicates a -2% error on i20 and +2.8% error on Jetta. It could also be worse - the actual distance is only 340km which will make i20 to have a +ve error and Jetta with a worse error.

2. Change in circumference of the tire due to tire wear. The car calculates the distance based on number of revolutions made by the wheel. As the tire wears, the diameter reduces and hence the circumference. So, for the same number of revolutions of the wheel, while the odo indicates a distance, the car would have traveled lesser distance. Below link has a calculation that indicates upto 2% error in distance measurement between a new and worn tire.

http://mechanics.stackexchange.com/q...eedometer-accu

So, the tire wear in i20 and Jetta would spread the error.

3. Change in circumference of the tire due to pressure difference. The rolling circumference of a tire with lesser pressure is smaller than a tire with higher pressure. I could not get a definite number for % change in circumference with respect to change in psi. As indirect TPMS systems (like the one in Octavia) are based on this principle, I am sure the change should be significant enough (may be 1%) for the system to detect. So, the comparison between i20 and Jetta could be affected by the tire pressures of the cars during these rides.

4. Difference in actual distance travelled by i20 and Jetta. It is practically not possible to have traveled the same path in both the trips. Between the two trips, there would be incremental changes in distance traveled due to lane changes, wide vs narrow cornering etc that could accmumulate over a long distance. Theoretically, these changes should average out, but still there will be some difference.

I would not consider VW app as a standard. The distance measurement on GPS depends on various factors. The absolute accuracy of the GPS on your phone, number of samples the app averages to calculate the route etc. Also, I doubt if VW app implements compensation for gradient of the route which itself could introduce a -ve error in the distance calculated by the app.

From all the above factors, the actual error on the Jetta may not be as bad as 4.9%. Even if you consider there is a 5% (just rounded off) error:

The odo would read 1,05,000km instead of 1,00,000km.
The speedo would show 105kph instead of 100kph.

As you rightly said, this is not very significant.

My suggestion: Have fun with the car instead of worrying about a 5% error on the speedo/odo

Just my 2 cents!
Oh, I am not really worried, just curious. Like you said, I am enjoying the car

Well, I agree that the VW app may not be accurate itself and also that my i20 may not have been accurate either. However, I do believe that the i20 was reasonably close to accurate since it matched Google maps on my iPhone practically every trip.

I have yet to compare Google maps with the VW app - that would determine how good the VW app is.

But the one glaring difference I see is the fuel consumption figures given by the MID and the one calculated by the tankful-to-tankful method. The MID gives me around 17 to 18 kmpl average and the tankful method gives me around 13.

I remember reading one ownership thread where the reviewer said the MID was pretty accurate re. consumption figures, but my experience has been completely opposite.

Cheers
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Old 18th July 2015, 11:26   #2028
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Default Re: Volkswagen Jetta : Test Drive & Review

Quote:
Originally Posted by tilt View Post
But the one glaring difference I see is the fuel consumption figures given by the MID and the one calculated by the tankful-to-tankful method. The MID gives me around 17 to 18 kmpl average and the tankful method gives me around 13.

I remember reading one ownership thread where the reviewer said the MID was pretty accurate re. consumption figures, but my experience has been completely opposite.

Cheers
There is at least a 10-20% difference in fuel consumption figures between the MID and the tankful to tankful method in my experience. My recent fill up gave me 15.22 kmpl using tankful to tankful method while the MID showed 16.7. I always stop at auto cut off while filling up.
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Old 19th July 2015, 11:28   #2029
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I find the breaks of my brand new Jetta (500 km) too bee too soft. Does not inspire confidence breaking on higher speed to a stop. In slower speed (40kmph) the breaking feels fine.

Does the breaks improve with run in? Can current Jetta owners share ear feedback about the breaks. Thanks!.
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Old 20th July 2015, 02:23   #2030
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Default Re: Volkswagen Jetta : Test Drive & Review

Here's hoping that the 'brakes' on your Jetta will indeed improve as the vehicle is run in and that it will not have a 'break'-down on that account

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Does the breaks improve with run in? Can current Jetta owners share ear feedback about the breaks. Thanks!.
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Old 20th July 2015, 09:01   #2031
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Default Re: Volkswagen Jetta : Test Drive & Review

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Originally Posted by PULAPIPL View Post
I find the breaks of my brand new Jetta (500 km) too bee too soft. Does not inspire confidence breaking on higher speed to a stop. In slower speed (40kmph) the breaking feels fine.

Does the breaks improve with run in? Can current Jetta owners share ear feedback about the breaks. Thanks!.
I feel it could just being you getting used to the new car... when I moved from my vRS, I found it too soft, but on the highways the car stops without a fuss and drama! Initially, I also found the body roll to be higher but got used to it after a few 100 KM's...
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Old 20th July 2015, 12:29   #2032
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Hi, I have a 2013 jetta comfortline and I want to retrofit cruise control. Can anyone guide me on this? Can it be done if I change just the stalks or I have to change the steering module as well?
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Old 20th July 2015, 15:29   #2033
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Default Re: Volkswagen Jetta : Test Drive & Review

Quote:
Originally Posted by PULAPIPL View Post
I find the breaks of my brand new Jetta (500 km) too bee too soft. Does not inspire confidence breaking on higher speed to a stop. In slower speed (40kmph) the breaking feels fine.

Does the breaks improve with run in? Can current Jetta owners share ear feedback about the breaks. Thanks!.
I have the same feeling with my jetta's brakes. I thought it was my car only.
I had to execute a couple of panic braking maneuvers my initial days of ownership. The brakes definitely lack bite and feedback in my opinion especially at higher speeds. I even took it to the dealer and they said everything is fine (I did not expect them to accept any fault and I had to tough time explaining what I experienced).
Having said that, that car does stop without any fuss except you have to get used to the feel of the brakes (aka press harder). I have got used to the brakes now and no more panic braking since I know exactly how much pressure to apply.
Whenever I drive my other car (ritz), I end up braking hard nowadays for the first couple of kilometers as I apply the same pressure as the jetta.

If you do end up taking it to the dealer and they do end up finding something wrong, do let me know
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Old 20th July 2015, 21:28   #2034
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I have experienced the newer jetta model of a friend and found the bite when braking to be quite less compared to the earlier model, have not tried out the vehicle of late, in the earlier model the bite was there right from the start, also the engine pull seemed subdued, maybe a one off case
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Old 22nd July 2015, 17:06   #2035
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Default Re: Volkswagen Jetta : Test Drive & Review

Quote:
Originally Posted by etrast75 View Post
I have the same feeling with my jetta's brakes. I thought it was my car only.
I had to execute a couple of panic braking maneuvers my initial days of ownership. The brakes definitely lack bite and feedback in my opinion especially at higher speeds. I even took it to the dealer and they said everything is fine (I did not expect them to accept any fault and I had to tough time explaining what I experienced).
Having said that, that car does stop without any fuss except you have to get used to the feel of the brakes (aka press harder). I have got used to the brakes now and no more panic braking since I know exactly how much pressure to apply.
Whenever I drive my other car (ritz), I end up braking hard nowadays for the first couple of kilometers as I apply the same pressure as the jetta.

If you do end up taking it to the dealer and they do end up finding something wrong, do let me know
The brakes have worked fairly OK for me. In the couple of panic braking situations that I had faced on our interesting highways, the car does come to a halt without any fuss & at a reasonably short distance.

The pressure with which you press the pedal varies from car to car. My friend (who owns a corolla) kept pressing the pedal of the Jetta too hard when we went for an initial drive in my car, bringing it to a jerky halt. While for me, unless I am braking hard, I do tend NOT to press the pedal very sharply / forcefully & have not faced any issues in normal driving conditions.

Having said that in the past couple of months I have seen the ABS come in play a few times now - which tells me that I need to get my NCT5s changed up without further procrastination
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Old 23rd July 2015, 11:11   #2036
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Default Re: Volkswagen Jetta : Test Drive & Review

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Hi, I have a 2013 jetta comfortline and I want to retrofit cruise control. Can anyone guide me on this? Can it be done if I change just the stalks or I have to change the steering module as well?
Cruise control is a useless feature in India - My vRS had one and I hardly could use it for a few 100 meters before hitting the brake!
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Old 23rd July 2015, 13:29   #2037
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Default Re: Volkswagen Jetta : Test Drive & Review

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Cruise control is a useless feature in India - My vRS had one and I hardly could use it for a few 100 meters before hitting the brake!
Times have moved on. I had it on my vRS but never used it much. With the improved highways in KA/TN, I use it a lot.
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Old 23rd July 2015, 14:12   #2038
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Default Re: Volkswagen Jetta : Test Drive & Review

Been following all the noise about the Hyundai Creta launch, which does sounds like an attractive package in the 16-17l range.

Also just found that the car (called ix25 in China) got a 5-star safety rating in the C-NCAP tests. This really gives me second thoughts about buying the Jetta (at almost 25l) 3 months back, maybe I should have waited a bit longer.

Anyone else having the same thoughts about their purchase?
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Old 23rd July 2015, 15:09   #2039
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Default Re: Volkswagen Jetta : Test Drive & Review

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Anyone else having the same thoughts about their purchase?
Hi Harry,

No second thoughts on the Jetta. Both of them are two different cars. I got to test drive the creta yesterday, it looks damn good no doubt but was not impressed with it. Test drive an AT version and your doubts may vanish. (I would love to wait for the Tiguan)
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Old 23rd July 2015, 18:54   #2040
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Quote:
Originally Posted by AirWind View Post
Cruise control is a useless feature in India - My vRS had one and I hardly could use it for a few 100 meters before hitting the brake!
It's true for most of Indian roads, I agree. But I was planning for a couple of longish drives and thought it would be a welcome addition. Anyway will install only if it's within a reasonable budget. Otherwise will just ensure my next car has it!
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