1st off, will A/C and power steering pumps will actually be visible?
2nd, will you include the power loss when they are turned on? (i know that small engines suffer, have no idea about the big ones)
Possibly, but I’m not sure what stats they’d really figure into. Paticularly as the power draw from those accessories varies a lot.
If one wanted one could have generic values for, say 3 different tech-levels of A/C units developed over time. A '60s era piston-driven A/C compressor would offer a certain amount of of comfort to any passenger those days but be heavy, expensive and eat close to 10% of engine power when running at full pöwer. I saw one of those things in a friends '73 Chrysler New Yorker and it looked basically like your small air-compressor with 2 pistons and all.
Later technologies could be the late '70s and '80s more slimmed and discreet compressors akin to todays units but eat something like 5% of engine power in a reference engine, and the last technology appearing in the late 1990’s with power-consuming down to something in the 3,5%-range, also including those who came after the ban on those freon-refrigerants that killed the ozone-layer.
It’s something of a long shot but if any stat like “Passenger comfort” or something like that makes into the game you could perhaps add a few “general” points for mounting an A/C-unit overall at the cost of a slightly higher price, slightly lower power and slightly more weight and a bit of higher service costs. Detailing it down to increased want for such devices in markets like southern Europe or the hotter parts of USA would just be brain drain though.
I get the notion that very very large cars with large V8’s, very soft suspensions, standard mounted A/C and power steering-seats-windows-mirrors and lots of chrome could be a sales hit in certain parts of the western world in Automation… 
Yup, This.
Hm, I would not say that the installation of a A/C unit should result in lower power. The power figures are usually given with all additional devices turned off (I’d say I use the A/C for less than 10% of my driving time). Furthermore, no manufacturer gives you the amount of power that actually reaches the wheels (so without losses in gearbox and differential), just the pure engine power.
Greets
Martin
No manufacturer does, but we will need to of course to calculate acceleration etc. Mind you we won’t be calculating acceleration with the A/C on 
i do like Raticons idea, please oh please take it into consideration at least 
Yeah, Ration’s idea is great.