[RobUK]

I've had this on occasion, one example was taking a familiar route where I'd turn left and the destination is 200yds away but the pro nav wanted me to go round the block a total of about 800yds. Other times it's taken me down a 10mph farm track for 2-3 miles instead of 60mph main road for 5-6 miles. I just put it down to crappy map data.