When we landed at BLR a few months ago, there was a long line of new, metered taxis just outside the terminal. Based on experiences elsewhere in India, we looked hard for a taxi booking office, but we were directed to just go outside and get into the first taxi in line. As we drove away the driver announced that he was turning on the meter. We were somewhat suspicious of the formality of this, but were overjoyed to see the charge when we arrived at our hotel. It turned out to be less than a sixth of what the hotel was charging for its one-way transfers ---- and, to my eye, they used the same style car for the transfers. Overall the efficiency was a shocking experience for us in India....and a sign that BLR really is different from everywhere else we travelled in the country. In short, I really don't think that it's necessary to prebook the transfer.