Hi Lawman,
I'll attempt to give a little more detail to what everyone else is saying
There are several reasons the in-dash GPS on many vehicles are not the greatest:
1) The quality of the dataset (i.e. the maps). There are many different data sets that various GPSes use. Some of them are government-produced, some of them will be maintained and created by private companies (Garmin, Google, etc) and some of them are public data sets maintained and distributed for free (Open Street Map). The public one is surprisingly good, some might even say the best. Typically the data sets used on in-dash Nav systems that come with new vehicles are not the best.
2) The quality of the software (i.e. the thing that tries to give you directions). Again, the software that comes built-in with most vehicles is junk. Dunno why this is, or why they don't just license it from Google but that's what we're stuck with.
3) Whatever comes with most vehicles doesn't seem to be updated very frequently (either the data/maps or the software).
So basically what everyone is suggesting is some variation of getting a system that uses better data and software, which is why Google Maps is a popular suggestion, or any one of the numerous apps you can get on iPhones and iPads that uses the OpenStreetMap data. They're all great.
If you are dead-set on having the in-dash version you can buy aftermarket systems to replace the Toyota one that have better GPSes but it's going to be a big pain and pretty expensive, which is why everyone is suggesting the cheaper/simpler option, which is:
- Get an iPhone or iPad with a GPS chip (if you want a bigger screen).
- Get some kind of a mount to attach it to your dash/console. There's a number of threads around here with lots of different suggestions.
- Get one of the good apps (GaiaGPS is one of the best) for it.
With the apps on a phone or iPad you don't need to be in cellphone range, as long as you have downloaded the data for where you want to go ahead of time. Most of the apps you can download whatever data you need - you can just go to the map, draw a big box around the area you want and the app will save it all for you. Then to use it, all you need is a GPS signal.
For example, I live in Lake Tahoe. I have downloaded all of the data on to my phone for most of Northern California and North-Western Nevada. It's always there regardless of whether or not I'm in cellphone range, and since I always have my phone with me I have excellent navigation on roads when driving, biking hiking, dirtbiking, snowmobiling etc. pretty much anywhere I want to go. When I get in my car I clip the phone in the mount and it's an in-car GPS. When I get out I put it in my pocket and it comes with me.
This is by far going to be the cheapest, easiest, and best way to get high-quality navigation data and good software into your 4runner.