This doesn't give the comparison between seated upright and full tuck,>but for example the difference between riding on the drops of the bars>vs riding on the tops is worth 90 seconds in 10Km, in still conditions.>90 seconds is 7.5%. Going onto aerobars increases the advantage to 120>seconds in still conditions, or 10%.>

But note that in a strong crosswind the advantage increases to 500>seconds, or better than 19%.