Nothing ground-breaking here, but while I was
test driving the new Micra, I decided to find out how much of an impact the A/C had on fuel consumption over a range of speeds.
(As an aside, these Micra results would also apply to the 1.6L Versa Note and Versa sedan. Same platform/drivetrain/components.)
I ran a bunch of bi-directional runs at 3 different speeds with the A/C on and off. The fan was left on the 2nd speed for all the runs, just toggling the A/C switch.
Results...
(Note: I graphed it for L/100 km, so those of you used to seeing graphs of "MPG" where the taller bar means better fuel economy, keep in mind it's reversed in this case.)
From: AC vs. MPG: impact of air conditioning on fuel economy tested - Micra-Forum.com
The average fuel consumption increase with A/C on vs. A/C off was
5.9%.
In retrospect, I wish I'd done a couple more 100 km/h runs, since it seemed to show that the A/C impact is smaller at higher speeds & engine loads. Though it makes sense that it would be, since you're covering more ground for a given power draw, plus the engine is probably sitting in a more efficient part of the BSFC map while it's providing that power to the compressor.
Code:
speed AC N. S. avg L/100 km*
60 off 4 4.1 4.05
on 4.3 4.4 4.35
on 4.3 4.5 4.37
off 4.2 4.1 4.16
80 off 5 4.5 4.75
on 5.5 4.7 5.10
off 5 4.5 4.75
100 off 6.3 5.6 5.91
on 6.6 5.8 6.15
(* Some of the averages are affected by rounded conversions of initial
readings that were taken in MPG)
