Thank you. I am conscious that a tourist is overcharged, so I try to be prudent in my assessments. I repeat we have to distinguish between rental time (whole day, but driver waits you most of the time) and hours of driving time, to estimate a fair price. Then, let me ask you for my better understanding:
1) what should be, in your opinion, the honest price for 3 hours, going to Barelang 4th bridge, wait we have our seafood lunch, return to Nagoya?
2) how much could it cost, in your opinion, the
fuel (just the gasoline) for 3 hours
driving around Batam?
About the question 2), I estimate:
40km/h average speed in the slow roads of Batam, = 120 km total, 10 l/km, = 12 liters fuel consumed. The web site
http://www.numbeo.com/gas-prices/cit...sia&city=Batam
says that 1 l costs 10.000 IDR in Batam

. What is the actual price??
If that's true, just the gasoline for 3 hours driving is 120k Rp!!
Based on that, 210k Rp for 3 hours by taxi does not sound expensive to me. The driver must earn something too, after all.
PS: you leave the disco at 2am? It's the hottest time! I leave at 5am, and I use ojek if I am alone
