Hm.. Though question.. 8)
ARTILLERY!!!
Tanks and Infantry can do very little without Artillery support..
(and Artillery very little without tanks and infantry...)
It's hard to pick out a best artillery vehicle, but I think that the Panzerhaubitze 2000 (Pzh 2000) is a mean thing!
Capable of firing 5 shells that lands simultaneous on the ground, range up to 40km...
(Multiple Rounds, Simultaneous Impact (MRSI))
And to you Humvee question:
You spelled it right, and the US Army still uses a lot of them.
It's original name is: High Mobility Multi-purpose Wheeled Vehicle, shortened to HMMWV.
That's where the name Humvee comes from.