Its not the input, its the output that counts. My 700 Watt wave uses 80-84 Amps DC
through the inverter (a Heart 2000). Although this implies roughly a 10% overhead in
the inverter, I was able to select a microwave (a Kenmore) that happened to be 10% more
effecient than others on the market.

I've looked an number of times and never found one significantly better than using an
inverter. In fact, most of the offerings are small microwaves with a cheap inverter.
Also, if you buy an "of the shelf" 'wave you can get all the features you want, and you
can look for one with the highest effeciency.

Ron Thornton wrote:
Do a Google search for "12 volt microwave" and you will find them.
They should be more efficient than running off an inverter where you
will lose 20-30% from the conversion. A 12 vdc microwave with a 1200
watt input will pull 100 amps from a battery. A 120 vac microwave
powered from and inverter will pull at least 120 amps for the same
power. In general, you are always better off with 12 vdc devices if
your supply in 12 vdc.

Ron