I owned one similar to this.. it worked fine for powering my laptop, however it would get hot.. and the fan was louder than I was expecting. It lasted right up to the point that my sons leg snapped it getting into the car when I had it plugged into the back seat power port.

If I were to do it again, I'd mount one under the passenger seat and run power cables directly to the battery.. and get one in the the 750 - 1000w range as they NEVER seem to put out what they claim they do, or if they do, it's for like 3 minutes before they shut down.