The Sienna isn't exactly a comparable vehicle to the 5, but a 2007+ Sienna is considerably faster than that (0-60 time).
Sienna FWD 7.2 sec / 15.7 sec / 0.76g
Sienna AWD 7.4 sec / 15.8 sec / 0.74g (winter tires for all)
Mazda 5 9.4 sec / 17.3 sec / 0.80g
Sienna FWD
http://www.caranddriver.com/reviews...007_honda_odyssey_comparison_test+page-5.html
Sienna AWD with winter tires
http://www.caranddriver.com/reviews...oyota_sienna_limited_awd_short_take_road_test
Car and Driver earlier published 0-60 times as low as 6.7 sec for the Sienna FWD -- which is possible if manually shifted. The biggest challenge is keeping the tires from letting go -- which do let go in 1 and 2 with no problem, and 3 if shifted late, from 2.
Mazda 5
http://www.caranddriver.com/buying_...ring_short_take_road_test+t-specs+page-2.html
I'm not sure that the manual 5 speed is going to be much, if any, faster than the auto 5 speed. A torque converter isn't a bad thing, for acceleration, if it keeps the engine at a higher rpm during the event. The biggest penalty is going to be weight. If the auto is shifted manually, the times are going to be pretty close.