14K with racks - real world data

[ajrowell]

Hello all,

I now have over 15K on my Prius and have had Yakima 58" racks along with 2 Yakima bike trays attached to the roof for 14K of them, since I ride 3-4 times a week. I additionally have the fairing attached to the front. Now for the data.

Since placing them on the roof I have averaged 47.3 MPG. I drive conservatively and rarely exceed 70mph, even on the Interstates. I bought my Prius in January and drove the first K w/o the racks and got about 49.5 avg MPG. So not much different and I did not let it worry me since it was not costing me much in ($) to have the conveniece of racks on top to put my bikes on in a matter of seconds with no worries of dirt or chain lube getting on my beige (white) seats. But the price of gas in North Georgia is now $2.89 per 4 liters. This price coupled with the fact that I have not driven my Prius (w/o) racks in summer temperatures made me pull them off yesterday. I was a bit skeptical as to what the increase would be, estimating about 3 MPG in fuel economy improvement. To my amazement, I have gotten 54.6 MPG since pulling the racks off over the last 89 miles. I have not changed my driving habits, still driving conservatively (using pulse and glide when appropriate and a coordinated light right foot) but wow am I amazed. I knew I would do well, since I get better mileage than most with 5" of steel extending above my aerodynamically engineered rooftop, but 7 MPG difference was a surprise. So today I laid down the backseats and threw down a king size sheet and laid my bike in the back. Is it worth laying the seats down everytime and laying a sheet down, versus the racks, I don't know, but it sure makes me feel better getting 15% increase in fuel economy.

Take care, and remember to drive it like gas costs $3 a gallon.