I have one running in the garage all summer. It's not as effective as air conditioning, but it does keep the leather seat covers free of mold. I'd never use a built in drain pump, they are usually not reliable. Instead, I attach a hose and let it gravity drain into my sump, which happens to be in the garage. If the garage is at ground level, you can drill a hole in the siding and drain directly outside.

I'll tell you a secret: I got my dehumidifer for free. There's a site called Merchrebate.com where they have a very limited range of goods. You buy a product, and they pay you to review it..the payments approach the price of the goods. I have no idea how they make that business profitable, all I know is that free worked for me.