LPG V70 2001 26Tkm/year worth it?

Hello forum, I’m back to their LPG thing. Now I have to calculate with an annual mileage of approx. 27,000 km with 2 autogas computers in the net that the installation is amortized after just 2 years. After that save approx. 850€/year. Here in the forum I read partly that this is not worthwhile at the annual running performance. The car is BJ 2001 and has now 95.000km down. I bought it used to a year ago. What’s right now?? btw: Does someone know an experienced change. ster in the area Karlsruhe (+Umkreis 100km)? The dealer where I bought has been upgrading for a few months. I don’t know, however, how fit it is in the short time already…. Or do you want to go to the WW?