Comment 27 for bug 195483

It seems the only way to get gstreamer to work the way you want is to override every one of its settings with something you want. I was finally able to use this pipeline:
audio/x-raw-int,rate=44100,channels=2 ! lame name=enc mode=0 vbr=4 vbr-quality=0 quality=0 vbr-min-bitrate=32 vbr-max-bitrate=320 lowpass-freq=25000 ath-lower=0 ! id3v2mux

to get insane-quality VBR files equivalent to
lame -m stereo -q 0 --vbr-new -V0 --add-id3v2 {infile} {outfile}

I used VLC's statistics feature as suggested above and found these files to have the same stream bitrate and variability with files created by command-line invocation of LAME using the above parameters.

gstreamer definitely needs some way of invoking LAME with only the overrides provided in the pipeline instead of specifiying its own (difficult to decypher) defaults.