Originally Posted by Anorak
The HIR2/9012 in the Volt is supposed to work almost as well as an H.I.D. without the complexity and expense of an H.I.D.
is an explanation
Typical GM "inside the box" thinking. HIRs were developed back when HIDs were ridiculously expensive even for OEMs buying by the thousand. Today OEM quality HIDs can by had from China for only slightly more than a standard bulb.
HIRs are great if you want to retrofit them into reflectors designed for 9005 or 9006 bulbs, but they are a cop-out if you designing a $40k car.