Regenerative air-conditioning; my unnecessary technique to improve comfort (a little)
 

"Regenerative" air-conditioning: in a situation where it is deemed necessary or expedient to waste kinetic energy for whatever reason (i.e. a stop sign at the bottom of a hill, freeway off-ramp in crowded conditions, etc.), put the car in gear with accelerator released to drive the crankshaft, no instantaneous fuel consumption due to DFCO. Now turn on the AC and enjoy a brief "free" cool-down. Crank the fan up to also take advantage of free alternator charge and to maximize AC compressor utilization. Slow down early (where practical) to extend the duration of the deceleration period and increase the amount of cooling received.

However, do not let yourself "accidentally" create wasted momentum just to get the "free" cooling; that may end up consuming more fuel than just turning on the AC and letting it run like a normal person.

I thought this up while hauling the family, I was thinking it was too early to require AC, although it was getting pretty warm at 11 am, when I descended a steep hill and realized it was an opportunity. Why throw that energy into the brake pads when it could be doing something useful: making the kids less irritable.

100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com

88) Cycle the A/C if you have to use it

If you have to use the air conditioner, set the air flow to recirculate and manually turn the A/C on and off as needed. For greater efficiency, switch it on when under light engine loads or deceleration fuel cut off and off when under moderate/heavy loads. (Note: some newer vehicles do this automatically.)

;)


At least on my car, having used the AC, the fresh air apparently gets drawn in over the chilled cooler, and remains cold (colder than ambient) for a while.

Another thing you can do is open all the windows and enjoy the wind. It's easier to not waste gas that way, and personally I prefer a nice breeze over air conditioning in everything but the hottest of weather.