nav system: predicted trip times overstated

[lrindt]

Just purchased 2007 M45. The nav system (using Navteq version 7.4 DVD) consistently overstates the trip/travel times. I entered a 90 mile trip that was on the interstate for 95%+ of the trip and it comes up with a trip time of over 160 minutes (at posted speeds should not have been more than 90 minutes). Using several different destinations, the trip times consistently come up to an average of about 50 mph- even though the trip is on interstates and freeways.

I drilled down in the Voice Guidance section of the settings and changed the "average speed" setting from the default (top option) and set the assumed speed on each of the road types (freeway, main road, city streets,etc.) to 70 mph for freeways and the max number allowed on the other streets. Using those entries, the prior average speed of about 50 mph was increased to about 60 mph. However, that still overstates the travel time by a lot when I plug in a trip from Vegas to LA. It's all interstate and an average of 60 mph is well under what the posted speed limits (70-75 mph) are.

Anyone else experienced this issue? Any luck at resolving it? Thanks for any info you may have to share on this.

[NightWatch]

This is not something peculiar to the 2007 model year or even to Infiniti. I have noticed this on my 2003 coupe, my 2007 G35 Sedan as well as two different Garmin Nuvi GPS units. Even my friends Acura RL's nav system has the same faults. I've noticed that it is less accurate on longer trips with multiple routes or way point. I think the algorithms used to calculate time to destination have too many variables to calculate accurately. Generally I just look at the route, and the number of miles and knowing my driving style I have a pretty good estimate barring traffic issues of how long it should take to get there.

[ken in az]

It calculates bathroom breaks and for when you get behind that slow azz minivan that you can't get around for 20 minutes - lol

[lrindt]

Thanks for your feedback. Doing the math using the miles and estimated mph will give you a good estimate...regardless of the nav estimated time. My experience to this point was with two fairly inexpensive Garmins and they actually did a pretty good job on hitting accurate times. Barring any solution surfacing, I'll plan to calc my own travel times (like I would have anyway) and take the nav times with a grain of salt. Thanks again.

[kkalahiki]

Thanks for your feedback. Doing the math using the miles and estimated mph will give you a good estimate...regardless of the nav estimated time. My experience to this point was with two fairly inexpensive Garmins and they actually did a pretty good job on hitting accurate times. Barring any solution surfacing, I'll plan to calc my own travel times (like I would have anyway) and take the nav times with a grain of salt. Thanks again.

Henderson(St. Rose on ramp to the 15) to LA(Orange County) average speed of 90-95 got me there a little over 2 and a half hours. Very few spots got up to 100.

[palincal]

It is a problem with the database provider (navteq, teleatlas etc.) and not the GPS maker (infiniti, honda, garmin etc.). Looks like the speed for a given freeway or a section of the route was incorrectly recorded. I have seen this happen on garmin when a 20 mile trip was showing 4 hrs. I guess a big chunk of the route was marked as 5 mph in the database. I haven't seen this problem with my car so far.