In raising Bug 871, Nicola alluded to a proposed reorganisation of the support for vehicular communications in the ns-3 wifi module. Other elements of Bug 871 have been addressed and with the ns-3.9 release pending this new bug seperates out the unfinished work.

Nicola's comments in Bug 871 were:

4a) IEEE 802.11p and IEEE 1609.4 (WAVE) say that OFDM_5GHz_10Mhz is used as-is,
so we don't need a new WifiPhySpecification. 

4b) for vehicular communications, QoS support (802.11e) is used, but with
different parameters than regular 802.11; this was the main reason why
changeset 5747 introduced the WifiPhyStandard 80211p_CCH and 80211p_SCH. Since
this is really a MAC issue, and not at all a PHY issue, it should be solved by
creating a new WifiMac (say WaveWifiMac), and having a new 

4c) changeset 5747 affected also Qsta and Qap, but this should not be the case,
as vehicular standards define their own BSS  - they call it "Wave Basic Service
Set (WBSS)" - and they do not use the regular association/deassociation
procedures. Using Qadhoc as a substitute makes sense, but not using Qsta/Qap.
(my apologies for not reviewing the patch that became changeset 5747 when it
was time...)