I got this message after my 120 mile commute today (60-70mph), but I think I had a little bit of a tail wind. I usually see a maximum of 44.3 mpg on this same drive so I'm not contributing this mileage to the new thermostat.... yet.
Here are some of my hand calculated tank full averages for the last few fill ups (mixed hwy and city driving during Jan-Feb-Mar = cooler weather):
1/07/2018: 36.05
1/15/2018: 37.88
1/21/2018: 37.26
1/28/2018: 37.16
2/11/2018: 36.74
2/19/2018: 38.05
2/25/2018: 37.78
3/11/2018: 36.98
3/18/2018: 38.68
I may be able to see some improvement when I fill up on Sunday and moving forward. Will post up my findings as I get them.
EDIT:
03/25/2018: 39.63
04/01/2018: 39.28
04/08/2018: 38.76
04/15/2018: 37.40
04/29/2018: 36.98 (more around town than normal)
05/11/2018: 38.09
05/20/2018: 39.68
05/27/2018: 39.21
06/03/2018: 39.54
06/10/2018: 38.91
06/17/2018: 38.68
06/24/2018: 38.55
07/01/2018: 40.30 (more highway than normal)
07/04/2018: 39.90
07/08/2018: 40.88
07/15/2018: 39.84
07/22/2018: 37.46
07/29/2018: 36.98
08/05/2018: 38.06
08/12/2018: 37.18
08/19/2018: 36.87
08/26/2018: 38.18
09/02/2018: 37.51
09/09/2018: 39.57
09/16/2018: 37.83
09/23/2018: 37.58
10/05/2018: 36.46 (had emissions modification done this week)
10/15/2018: 37.24 (more highway than normal)
10/21/2018: 35.94 (48,000 miles of this is going to suck)
10/28/2018: 36.44
11/08/2018: 35.90
11/15/2018: 35.91
11/29/2018: 37.98
12/06/2018: 36.40
12/14/2018: 36.66
12/20/2018: 36.82
01/03/2019: 38.03 (more highway than normal)
01/06/2019: 35.96
01/13/2019: 35.80
01/21/2019: 36.70
01/25/2019: 35.17
01/30/2019: 36.12
02/08/2019: 34.88
02/12/2019: 36.28
02/20/2019: 34.22
03/05/2019: 35.06
03/14/2019: 33.36 (holy crap)
03/20/2019: 35.75
03/31/2019: 37.07
04/07/2019: 36.56
04/14/2019: 36.63
04/21/2019: 35.64
05/02/2019: 34.77
05/12/2019: 37.21
05/19/2019: 35.12 (Intermittent DTC: P0401)
05/27/2019: 35.57 (Intermittent DTC: P0401)
06/02/2019: 34.94 (Intermittent DTC: P0401, P2002)
06/09/2019: 34.59 (Intermittent DTC: P0401, P2002) Going to VW in the morning (They say new DPF needed. Parts ordered will call when in)
06/16/2019: 35.60 (Intermittent DTC: P0401, P2002)
06/24/2019: No Data because VW cleared trip memory during DPF and EGR Filter replacement.
07/04/2019: 34.68
07/07/2019: 37.90 (more highway than normal)
07/18/2019: 33.30
07/26/2019: 35.16
08/02/2019: 34.67
08/08/2019: 34.61
08/16/2019: 34.56
08/22/2019: 36.33
08/30/2019: 36.13
09/05/2019: 36.10
09/13/2019: 36.95
09/22/2019: 36.21
10/04/2019: 35.36
10/11/2019: 35.93
10/18/2019: 36.24
10/25/2019: 37.15
10/31/2019: 37.47
11/11/2019: 36.50
11/17/2019: 36.24
11/24/2019: 37.04
12/01/2019: 37.59
12/07/2019: 37.94
12/16/2019: 35.31
01/06/2020: 35.13
01/16/2020: 35.23
01/24/2020: 35.37
01/31/2020: 34.21
02/06/2020: 36.55
02/14/2020: 35.63
02/21/2020: 36.41
02/28/2020: 35.24
03/06/2020: 34.47
03/15/2020: 36.88
03/22/2020: 34.93
03/29/2020: 35.87
04/10/2020: 36.50
04/19/2020: 36.13
04/27/2020: 37.04
05/03/2020: 35.60
05/10/2020: 36.09
05/17/2020: 36.64
05/24/2020: 36.63
05/31/2020: 37.14
06/07/2020: 34.66
06/15/2020: 36.21
06/21/2020: 34.87
06/28/2020: 35.64
07/05/2020: 37.39
07/12/2020: 35.58
07/19/2020: 36.28
07/26/2020: 35.64
08/02/2020: 36.87
08/09/2020: 35.84
08/17/2020: 36.26
08/29/2020: 35.72
09/04/2020: 34.72
09/10/2020: 37.53
09/17/2020: 35.69
09/24/2020: 37.53
10/29/2020: 36.19
11/05/2020: 35.70
11/11/2020: 38.62
11/30/2020: 38.41
12/10/2020: 35.23
01/08/2021: 37.30
01/15/2021: 37.19
01/22/2021: 36.80
01/29/2021: 37.30
02/11/2021: 35.82
02/26/2021: 35.27
03/25/2021: 37.44
04/02/2021: 35.34
04/30/2021: 36.91
05/06/2021: 36.27
05/12/2021: 37.85
05/21/2021: 36.95
05/27/2021: 35.84
06/05/2021: 36.12
06/11/2021: 36.96
06/25/2021: 37.70
07/02/2021: 36.69
07/09/2021: 37.38
07/16/2021: 35.85
07/23/2021: 36.53
07/30/2021: 35.84
08/05/2021: 36.88
08/12/2021: 36.04
08/20/2021: 35.46
08/26/2021: 37.50
09/03/2021: 35.81
09/09/2021: 37.19
10/01/2021: 36.49
10/07/2021: 36.69
10/15/2021: 36.22
10/21/2021: 36.09
10/29/2021: 35.86
11/05/2021: 36.95
11/10/2021: 36.85
11/19/2021: 36.89
12/03/2021: 36.50
12/10/2021: 37.62
12/17/2021: 37.84
01/02/2022: 39.95 (more highway than normal)
01/14/2022: 35.63
01/21/2022: 37.96
02/03/2022: 38.37
02/11/2022: 36.19
02/25/2022: 37.40
03/04/2022: 35.40
03/18/2022: 35.96
03/25/2022: 34.73
04/01/2022: 35.87
04/08/2022: 36.37
04/17/2022: 36.14
04/29/2022: 35.64
05/06/2022: 35.96
05/13/2022: 35.35
05/20/2022: 36.13
05/27/2022: 34.48
06/03/2022: 34.27
06/09/2022: 37.38
06/17/2022: 34.61
06/23/2022: 35.23
06/30/2022: 36.04
07/07/2022: 35.22
07/15/2022: 35.00
07/22/2022: 33.44
07/31/2022: 37.56
08/07/2022: 35.24
08/14/2022: 37.54
08/21/2022: 36.04
10/14/2022: 35.60
10/21/2022: 36.74
10/28/2022: 37.28
11/04/2022: 36.19
11/10/2022: 36.98
11/18/2022: 38.07
12/02/2022: 35.92
12/09/2022: 35.06
12/16/2022: 35.41
12/22/2022: 36.65
12/31/2022: 37.37
01/06/2023: 37.54
01/13/2023: 37.46
01/20/2023: 37.25
01/27/2023: 36.25
02/03/2023: 35.27
02/10/2023: 36.89
02/16/2023: 36.48
02/24/2023: 35.41
03/03/2023: 37.62
03/10/2023: 35.83
03/15/2023: 35.96
03/17/2023: 36.97
03/22/2023: 36.75
03/31/2023: 37.07
04/05/2023: 35.81
04/28/2023: 35.35
05/12/2023: 36.78
05/18/2023: 38.17
05/26/2023: 38.59
06/02/2023: 38.01
06/09/2023: 37.64
07/01/2023: 35.86
07/07/2023: 36.95