Rickenbacker said:
my UP seems to get slightly better mpg in the warmer months even with air con on.
With the warmer air you get less air resistance. Petrol engines generally like warmer intake air too, and they obviously warm up quicker, which all helps to reduce fuel consumption. So you can still get better fuel consumption despite running the AC .
On the CNG up, you can really feel the power drain from using the AC.
Acceleration is even slower and takes more fuel, while idle fuel use is doubled to 0.8kg/h with AC on.
The roads I've taken with the AC on full tilt, would normally take 3.0 to 3.2 kg/100km (indicated) without AC. They now took 4.6 !
The math kind of fits though.
Using like 0.5h to do around 25km, would add 0.4 kg to 25km, or 1.6kg to 100 km.
Only one solution : drive faster with the AC on