Garmin Nuvi 3790T Review

By reuben, 24 July, 2010

I bought one of the Garmin Nuvi 3790T's last week to replace my Tomtom 930 which has suffered multiple catastrophic failures (separate story but I made a point of not buying another Tomtom due to issues which I considered to be quality related and then a subsequent support issue which I was very unhappy with).

I originally posted some feedback0 on Whirlpool ( but thought I would extend this to a more complete review on my own website - and this is it.

Note that I am located in Australia, so comments in regards to the maps relate to the maps that I have of here.  Obviously I cannot comment on the non Australian maps, although I do hope to be able to test out the NZ Maps in the coming months when I next make a visit home.

So to start with, you can find the manufacturer's website and of the product here:

Now onto the details.

Starting with the good things about this unit - the hardware on the 3790T is superb. It looks ultra sexy, extremely appealing and can easily fit in one's pocket – great for when leaving the car when not wanting to leave the unit actually in the car.  It's the hottest thing out when combined with the genuine Garmin case, which is a beautiful leather pouch that hugs the shape of the already thin Nuvi just nicely.  It really just reaches out and says "touch me!".

The combined TMC and power cable that the unit ships with works well - it sucks hard to the windscreen and is nicely all bonded together as one single cable (rather than having a TMC antenna dangle off separately).

The Nuvi software is great to use.  The icons are neat, it's easy to use and most of all, it's intuitive.  You don't need to be a tech genius to be able to use it.  One of the key criteria I have when assessing anything technical - be it a personal purchase like this or a multi thousand dollar purchase like an appliance at work - is that I can turn it on and within 15 minutes have whatever it is actually do what I want (which is usually something basic) without me having to jump through dozens of hoops and get a Ph.D along the way.  If I can't get an outcome in 15 minutes it fails.  My philosophy is not about avoiding reading the manual (I do read the manuals), but I am of the view that a well designed device of any sort has had some thought put into ease of usability, and should be able to cater for a completely non technical person.  To do that it must be usable to a tech-savvy person like myself in a relatively short space of time also.  That's my view, and I actually enjoy some pretty complex things like Unix that are very much not at the "trivial" end of the user friendly spectrum :-)

Featurewise, the voice activated navigation is brilliant. You can literally get in the car and tell it verbally where you want to go and it will take you there. And after a while of it not being told it will actually work out where you are going using Nuvi Routes.  Clever, kinda obvious when you think about it, and well done.

Traffic TMC locks on and updates frequently.  Unlike the Tomtom Go930 which replaces this unit, it's quick to find the TMC signal and update.  One of the main reasons I bought the TomTom with the TMS was for TMC and it was so disappointing, so it's great to find a working implementation!  Arguably the actual TMC service is a bit...unreliable, but at least the unit does a good job of handling what data it does get.

Security has a neat feature whereby if you are within your home location the unit does not require you to enter a PIN.  If you are not it requires a PIN.  Obvious, great and clever.

The voices that come with the unit are good - no real issues there.  They sound human and read our Australian street names pretty well.  I'm yet to try it in New Zealand, it'd be interesting to see how it would handle navigating names such as Tutanekai St or Whakarewarewa in Rotorua (NZ).

The built in POI's are comprehensive although they seem to be always doubled up, ie I always get TWO POI entries for each thing I search for.  A bug in the software I assume, but a minor one nonetheless.

Photos of the offramps on a motorway exit are great - although clearly not complete.  Having a photo of the offramp come up before I get to it is really good, so as a driver I know what I am looking for.  A pity that the image only appears on the screen for about 3 seconds and there seems to be no obvious way to make it stay up or return if I happen to miss the quick visual.

Onto the not so good things.

Unlike the TomTom the unit does take a bit longer to lock onto satellite signals when it's first switched on.  It does lock on eventually but unlike the 30s lock ons that the TomTom used to get, this unit takes more like 2-3 minutes.  Not a big issue, but a regression nonetheless.

Map errors are terribly common and there is no obvious way to report them, except via the Garmin website via some non obvious link.  If Garmin want to get accurate maps with errors being reported they really need to make this a lot easier.  It's simply way too hard for the average user to report an error.  Even just a "Mark this location as a map error" option on the main screen with the ability to submit this online for the next round of map updates (and assuming that they do push the updates upstream) would go a long way to making it easy to fix up many of the silly bugs.

The last point would not be that much of an issue except the maps generally though leave an AWFUL LOT to be desired.  The maps are full of errors, mostly relating to turn restrictions.  

The unit frequently plots routes that require turns that simply can't be done.  No left turn?  Oops hmmm.  No right turn?  Nope, that hasn't been possible for the last 6 years...ugh...  It would however be good if the speed restrictions were taken a step further in so far as school zones marked as 40 km/h zones during actual school terms and hours, even if it the dates of school terms needed to be manually added.  For the sake of a ticket I'd willingly manually enter them by hand.

Speed limits on the other hand of most roads seem to be pretty up to date and take effect quickly after actually passing a speed limit sign on the road.

The other huge flaw in the unit appears to be the actual route calculations/pathing.  In the 8 journeys I have done from various locations around Sydney to other locations within the metropolitan area, the unit has made a complete hash up practically every one.  6 of those 8 were completely ridiculous, and I mean really really insane and involve 150km+ detours out of the way.  For example a 6 km trip from Marrickville to home (Arncliffe) the Garmin wanted to take me 160km round trip, via Windsor.  A trip between home (Arncliffe) today and destination suburb Miranda was apparently best to go via Wollongong with an estimated 80km round trip.  Last night a trip from Mortdale to home (Arncliffe) was supposedly best routed via the ED and then M4 via Lithgow then back via the M7.  In all cases the unit wanted to send me via these ridiculous routes only to do a U turn at the far end, or in the case of Miranda to Arncliffe it wanted me to go down the Princes Highway south nearly 40km and then back again on the other side of the road.  Insane, I mean, really really ridiculous, and astonishing that a unit has been released to marked with phenomenal logic errors.  This is not corner case stuff, this is every route that I have attempted to use the unit on being totally wrong.  Clearly there are some major issues with this aspect of the system which I am hoping are resolved in subsequent builds of software.

An additional issue I have noticed is that frequently the unit will appear to get stuck when recalculating, which results in a 2-3 minute delay at about 80% through the recalculation.  This means I have no idea when driving whether I am on the right track or not, although in most cases the eventual result is a proposed route that is preposterously stupid anyway.  This is often followed a few minutes later by a complete failure of the unit at which point it does a spontaneous cold boot and everything is peachy again.  Presumably this is a software bug that I hope will be addressed in upcoming firmware releases.

I've logged a couple of support tickets with Garmin to try to resolve some of the problems, so far they have suggested a "factory reset" which I did (although you have to wonder how a factory reset can resolve a major fault with the unit on only the second time it was turned on).  I have kept sending information only to be told they are "looking into it" and in the latest email, that I should take it back for exchange.  But it's clearly a software not a hardware fault so I really can't see how an exchange unit with the same software and maps would possibly help.  My last email to them included screenshots and a complete text dump of the exact paths and GPS co-ordinates at the time of the fault.  I will be calling Garmin to speak to a human about this in the coming days.  They are however responsive and do email back quickly, but I'm left to wonder how much the front line support people actually know and what ability they do have to resolve complex faults and if the people who actually write and software and fix the bugs know what a mess they have created.

So to sum up, in my view the hardware is superb, the UI is second to none, but the software has a "few" major flaws.  It's completely unreliable in the first build of software in so far as accurate navigation from point A to point B. Which is quite a problem given that that is exactly what most people buy the unit for as it's primary purpose.

There are no new updates of any sort for the unit yet, and my unit has these versions:

- Software 2.20/Audio 1.70/Text 2.05/GPS Firmware 2.20/Bluetooth Firmware 2.20/PMIC version 819/TSC Version 1.16
- Maps, Basemap Worldwide Autoroute DEM NR 5.00, All other maps version 2011.10, I have the cityXplorer Sydney map as well as the AU/NZ map

Given the unit is so new, I am hoping and expecting that subsequent builds of the software will fix up these things and make it into a truly all round Navigation Device gem.  It has the makings of a stunner. But if you are looking for a well tested unit that can accurately plot directions from A to B when you yourself have little idea where to go, then this is most certainly not yet quite the unit to get just yet.

Overall, I'd give the unit a 4/10, I would give it at least a 9/10 in a heartbeat if the navigation and route calculation algorithms were reliable and sensible.

Update: 09/Aug/2010 - After much playing around, a replacement hardware unit, and eventually another round of support calls to Garmin, I determined that the cause of the navigation problems was due to the loading of the City Explorer maps on the device along with the inbuilt map.  The end result of the matter was that we determined that the unit does NOT work well if BOTH maps are loaded.  You will get all sorts of spurious navigation errors and the device will not work well with both maps.  This is not documented on the Garmin website, so buyer beware - do not purchase the City Explorer maps for a region that your device already has preloaded maps for, despite the sales information on the Garmin website indicating that the City explorer maps offer extra pedestrian detail.  They may - but these maps do not co-exist nicely.  Buyer beware!

I spoke to Garmin Support here in Australia about this and they advised that the City Explorer maps were intended for people who wanted to purchase the map for occasional use in a city/region outside those that were preloaded on the device.  I suggested that if this was the case then the website really should be updated to state this clearly prior to purchase, this as it does not in any location on the site (as far as I could find) indicate that was the case, and that without knowing this no potential purchaser was in any position to make an informed judgement as to if these maps were of benefit or not.  The Customer Service person I spoke to was not very receptive to this, which was disappointing.

Now that I have disabled the City Navigator maps the unit is working much better.  It is often preferring to take me down back streets and routes that take you through locations that are well off the beaten track.  In many cases this is actually good, the unit also tends to prefer avoiding traffic lights and intersections.  Many of the routes chosen will take you down narrow laneways lined with rubbish bins and garages to avoid lights and intersections - often obscure but still very valid routes, which in many cases are actually good choices.  Certainly not routes I would have chosen if I was navigating by street directory.

In light of that I would be happy to give the unit 9/10 for both Navigation and ease of use.  I'm now a very happy 3790T owner and I would recommend these units to anyone who is looking to purchase a navigation device or upgrade from a previous generation of unit.