A/C plug engine warmer ?
 

I live in an apartment and cannot have a cord going out to my car.
Is there an engine warmer that is available that doesn't need to be plugged in.?
I would think that one that runs off of the cig-lighter / A/C outlet would work (but probably not even be existant, because it would of course run down the battery overnight )

What are my options ?

The reason that I want to keep my engine warm ( despite this being 90 degree Texas weather ) is that from what I have seen, my MPG reading drops as much as 4-5 MPG just by having to warm up the engine.

I noticed that in the mornings when it was cool, my mileage would be around 4-5 MPG less than when I would get off of work. When I would get off of work, the car was warm from setting in the sun all day .
Despite having more red lights and very little, if any chance to coast in neutral, the day time runs always come out higher( MPG )

I had to go into work and work an overnight shift yesterday. As a result, I went in during the day, and drove home during the cool morning hours.
So basically my results were reversed : around 41 MPG to work and 35.6 MPG on the drive home.

Could engine warm up have anything to do with my mileage fluctuations ?

I plan to put my grille block back on, but this will only help the engine warm up faster. I need something that keeps it warm all the time.

I think you'll find that there's no easy solution to pre-warming an engine without access to AC power for a block/coolant heater. Or at least nobody has figured one out yet.

RH77 had been wondering the same thing because he often left his car parked at the airport for work trips, so he faced an icy cold engine on his return. Big downer for someone used to using a block heater @ home.

Another point to consider is that it's not just the engine but the entire drivetrain that benefits from higher ambient temps later in the day when you're seeing better fuel economy: your tire pressures will be higher; warmer rubber = less rolling resistance; lubricants in the wheel bearings is less viscous; transaxle oil is less viscous...

Engine pad heaters come in 12 volts but you would do well to have a timer on it. If you were running a deep cycle battery, like a yellow top or a regular flooded one, you could easily heat your block at work.
You might want to charge at home though because your alternator will be working overtime to charge that battery. Next level of difficulty would be installing a field coil switch to turn off your alternator for the drive home.

Good luck

What about insulating the engine compartment/drive system for the winter?

Don't know if you would need to find high temp stuff or if you could just buy a sheet of the blue foam insulation for houses. Specs on that stuff says max 75C/167F. I don't know if it would hold the heat in long enough for it to be warm by the time you get done working. But it would probably help in conjunction with a small block heater.

I also live in a location that doesn't allow me to plug in my car. One idea I had was a block heater connected to a second battery(deep cycle) that I could bring inside and charge. If you had a big enough battery you could have enough power to run the block heater on both legs of your trip. Depending on the battery setup you could use it to unplug you alternator during the summer as well.

You could route a coolant line through a copper pipe in an insulated box filled with some sort of wax or something that melts at a few tens of degrees below the normal coolant temperature. The idea is to let the wax melt when the engine is hot, thereby storing heat. It then uses the heat for a faster warm up next time. You could also add some heating elements to the box and maybe a secondary circulation pump so it can warm up even faster when plugged in. A thermal solar panel is another idea, although that would be tricky to implement.

Yeah, Mike's idea may be the best thing for you. I suggest looking up info on the Prius coolant thermos. You could fairly duplicate a simpler system fairly easily.