Well, if that is what "half tort" is, then it does not seem to apply to property damage (i.e., damage to her Touareg), especially if she is not at fault.
Her "loss" limitation will essentially be the fair market value of her Touareg before the accident. What she just paid for it may be an indication of FMV, but will not be conclusive of FMV.Since it is your vehicle, you tell them what you want for it, or tell them you want them to fix it.
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Lastly, your hole card in all of this is vehicle value. Since you just bought it 3 weeks ago, it's hard to argue that the price you paid for it (and the number you are asking for) is out of whack with market prices. You are the market.