I really wouldn't pay for RTTI - it's utterly rubbish compared to the level of detail you get with Google maps. It only works when there's loads of traffic (I presume because it only crowd-sources data from modern BMWs). Compare that to Google Maps which often knows how many yards long the queue at the next traffic light is!
I wish BMW would just licence Google's traffic info.
RTTI is not perfect and has many flaws but it’s well worth the 50 quid a year it costs and is genuinely useful on long journeys. So much so that I find the fact my GF’s Mini doesn’t have it is absolutely infuriating – a navigation system with no traffic flow information is frustrating to use.
Google’s feed is not perfect either, in-fact I’ve almost given up using it to predict long journey travel times now because of its over zealous prediction algorithms which means it seems to assume every serious motorway crash will obviously have eased up by the time you get there. It also constantly seems to route me through closed roads – it doesn’t seem to handle closures very well at all and numerous times I’ve had RTTI tell me a road is shut, Google try and route me through it, trusted Google over RTTI and found RTTI was right.
Google is absolutely great for regular commuting and city driving as generally in this sort of environment the prediction model works very well indeed but for a long trip where an accident could be anything from 15 minutes to 15 hours before its clear its pointless having any sort of ‘guess’ that it might have cleared by the time you get there, RTTI just assumes it won’t have and alerts you to the entire delay regardless of how far away you are which whilst not perfect is IMHO more useful for forward planning than the opposite.