Thats the working one:
t="m1abrams" createvehicle getpos player
Instead of "m1abrams" you can also use these:
"cobra"
"ah64"
"mi24"
"mi17"
"bradley"
"t72"
"t80"
"carrierw"
"papercar"
"jetrangersilent"
"seagull"
"soldierwb"
"generale"
"angelina"
There are many more things you can spawn, a complete list should be somwhere in the comref.
"t" is the name of the spawned object. For example, you can use "deletevehicle t", "t setdammage 1" or "player moveindriver t"...