This was an interesting study from leasing.com (apologies for the layout issues)

Outside temp / e-Golf range (heating/AC ON) / e-Golf range (heating/AC OFF)
-10° / 88 miles / 139 miles
-5° / 100 miles / 149 miles
0° / 115 miles / 157 miles
5° / 133 miles / 165 miles
10° / 153 miles / 173 miles
15° / 173 miles / 181 miles
20° / 186 miles / 188 miles

"Y mae dafad ddu ym mhob praidd"
1972 4/4, 1981 MGBGT, 1984 FLHT1340, 1980 XLH1000, 1990 ZX10