I think this thread is about someone using a motorcycle battery to start their car. They are interested in reducing the weight of their car for racing purposes & not much else. If you aren't interested in racing your Mirage or seeing it shed a few pounds, I don't see the point about arguing about all this?
Personally, I hate motorcycle batteries. Motorcycles, UTVs, & ATVs all have them. They can be expensive for what they are, but some are surely better than others. Personally, I've considered going the other direction with my Kawasaki Mule. The next time the motorcycle battery dies in my Mule I want to replace it with a cheaper, larger riding lawnmower battery. These batteries are typically $25-40 and available most anywhere for that price.
My 2006 Mule and 1993 John Deere (Kawasaki engine) riding mower have very similar engines. I've heard of others making some adaptations & going with lawnmower batteries on their UTVs , too.
I once kick started my Honda ATV for two years straight, because I got tired of replacing the battery every couple years. Adding a motorcycle battery to my Mirage is of no interest to me. Thus, I shouldn't even be here commenting!
I'll move on to another thread now.