Google Maps recommended "leave at" time: how reliable is this?

Google Maps provides a feature to estimate your arrival time based on typical traffic along your route. It provides this time as a range, e.g., "typically 1h - 1h 50m" Based on that, if you select to arrive at a specific time (vs. leave now or depart at), it will tell you what time to leave given the high end of the range.

My question is: if you follow the advice and leave yourself the high end of the estimated travel time range (1h 50m in my example above), how likely are you to arrive at your destination on time?

This is a rewording of this closed question: How is the range of Google Maps new drive time feature defined?

Best Answer

Google is surprising close to the estimate. I'm baffled each time I use it!

That being said, google has a pretty hard time estimating red zones. I've had google tell me a traffic spot will take 20 minutes, when it actually took me two hours! This is not normal of course (this was a highway in Brazil), but I still always just look at googles estimate as a whole (E.G. 1hr 50mn), look at the route it wants to take me through, and make my own judgments. I'd probably end up leaving 20 minutes before a google estimate of two hours.