I hated the original Prius. It had no right to call itself a "hybrid". It had one source of power: gasoline. This seriously confused the market and the press when the Volt -- a true Hybrid with electric and gas -- came out. I wish regulators defined the word "Hybrid" and limitied its use in marketing. Family Guy got the meaning of "Prius--and the type of self-righteous person who drove it--exactly right.
Let's say you are right: nobody really cares about the Prius price or technical specs and bought it to be seen. Now imagine someone buying something other than a Prius, say a BMW, or a Lexus, or even a lower end car like a Corolla who might dither over the color or trim package. How much ire do you have for those people being vain in caring what impression their car makes?
If you don't don't care about the non-prius scenario, it means you don't really care about the vanity aspect of car purchasing decision. Inspect what is really driving your resentment.