Hi, the 1.5 version appears to be a CPU hog and can drain a fully charged Galaxy S2 in under 90 minutes. I had no problems with version 1.4 and even after a 4 hour ride the battery would be at 50% plus.
To be sure it is not a phone issue, I ran the app on my newer Galaxy s5 and witnessed the same effect. Both phones got warm to hot on their backs showing the CPU was taking a hammering.
One final note is the app turns on bluetooth without asking and there appears to be no option in the settings to disable that behavior. I have to manually turn it off again each time.