Alfa Romeo Giulia Forum banner
1 - 11 of 11 Posts

·
Registered
2018 Vulcano Black Giulia Quadrifoglio
Joined
·
5,947 Posts
Discussion Starter · #1 ·
I have a gps based speedometer in my car and it is 2 mph lower than what my qv reports.

In my old car (a Honda) it always matched the cars speedo but with the Alfa it's lower.

Anyone know if the giulia is calibrated to be higher than actual speed?

Thanks
 

·
Registered
Joined
·
383 Posts
Mine's right on the dot. I know because I was tagged by a LEO at 68mph in a 55 a few weeks ago.

I was going 68mph :grin2:
 

·
Registered
2018 Vulcano Black Giulia Quadrifoglio
Joined
·
5,947 Posts
Discussion Starter · #3 ·
Mine's right on the dot. I know because I was tagged by a LEO at 68mph in a 55 a few weeks ago.

I was going 68mph :grin2:
Sorry about the ticket!

Guess I'll add it to the list of items for my 1 year service.
 

·
Registered
2018 Vulcano Black Giulia Quadrifoglio
Joined
·
5,947 Posts
Discussion Starter · #5 ·
  • Like
Reactions: wingler

·
Registered
Joined
·
647 Posts
All of my cars have read slightly over the actual speed. I am former law enforcement from way back and am very picky about my own speedometer and determining its accuracy.

My 2001 Honda Accord speedometer reads 3 mph high. My 2017 Giulia Q4 reads 2 mph high. I have checked it numerous times, several methods. It reads 2 mph high all the way up to 80 mph. Reads 27 at 25, 37 at 35, 62 at 60, 72 at 70, etc. I actually like it as I always use the digital speed gauge on the dash and it gives a slight bit of slack. I frequently use my cruise and for example will set it at 45 in a 40 zone (actually 43) and at 66 in a 60 zone (actually 64), etc. That varies some depending on the circumstances and gives me no tickets. For example some police will pull you over at a slower speed than normal on holidays.

I'm very comfortable with this and don't touch it.
 

·
Registered
2018 Giulia Q4
Joined
·
898 Posts
I downloaded a free GPS speedometer app on my iPhone and used that for a quick test. I also noted a 2 mph higherreading over actual, at 50 mph and at 60 mph. Will try other speeds when I go on a longer drive and can keep it constant.
 

·
Registered
2018 Vulcano Black Giulia Quadrifoglio
Joined
·
5,947 Posts
Discussion Starter · #8 ·
I had my winters installed last weekend. Michelin alpin pa 4 in oem size: 245/35r19 and 285/30r19

When I was checking tonight against my GPS, the speedometer is now 4 mph ahead!


I know the dealership said they updated the ECM and TCM. I'm wondering if this is the result of the update, or if something is up with the tires.
 

·
Registered
Joined
·
1,915 Posts
I had my winters installed last weekend. Michelin alpin pa 4 in oem size: 245/35r19 and 285/30r19

When I was checking tonight against my GPS, the speedometer is now 4 mph ahead!


I know the dealership said they updated the ECM and TCM. I'm wondering if this is the result of the update, or if something is up with the tires.
Tires are probably slightly different in actual size compared to "old" tires, due to being new, temperature, pressure etc.
This will have a direct effect on indicated speed ....
 

·
Registered
2018 Vulcano Black Giulia Quadrifoglio
Joined
·
5,947 Posts
Discussion Starter · #10 ·
Tires are probably slightly different in actual size compared to "old" tires, due to being new, temperature, pressure etc.
This will have a direct effect on indicated speed ....
I guess I'll give it time to settle in
 

·
Registered
Joined
·
317 Posts
You can check manufacturer specs. The aspect ratio sounds right. I altered the aspect ratio to fit a specific brand on our Cayenne. Despite a less than 1% difference the speedo is now 4 mph high instead of 2 mph high.

Sent from my HTC6545LVW using Tapatalk
 
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top