Does "live Traffic" from smartphone work well?

[Roadster]

I am considering upgrading the GPS to one that can receive live traffic info from a smartphone. The reason is that I dayly drive 20km/h on 110km/h congested roads and are quite sure that other road alternatives would be faster if the GPS just knew the actual speed on the different roads, not only the speed limit.

Will e.g. a Garmin 2597LMT solve this? I assume the FM receiver only alerts for queues due to accidents etc, not slow traffic in general, which the Smartphone link fixes?

How much data traffic is used on the smart phone when using this feature?

 

[Nuvi-Nebie]

Not sure, but I think the Blue Tooth link to an Android Smart phone is for " your GPS to receive real time information such as weather, PhotoLive Traffic Cameras, weather and much more", I can't find any info. about the Smartphone providing any extra traffic speed info.
BTW
The best Android App. for traffic speed I have found is called Waze, but I don't know if this info. can be used by a Garmin Sat-Nav via Blue Tooth