That is strange. 10 mpg and nothing on inpa. Weird. I know very little about the O2 sensors but some guys here are super smart on them, and I think inpa can tell you a lot about O2 sensor performance, which can help with troubleshooting.

__________________
Current
Original owner 2002 E53 X5 4.4i to 4.6i swap
2026 G80 M3 6 spd
2025 G06 X5 50e
Former
1972 Audi Fox
1986 Saab 900S
1996 BMW Z3
1998 BMW E36 M3 Sedan
2004 BMW E46 M3
2006 Audi A3 Quatro
1993 Mopar 318 Jeep Grand Cherokee
2015 V6 Jeep Grand Cherokee