My experience is that a spark plug thrown at tempered glass will break the whole glass out from a safe distance.
Long story: My former business was in your average industrial park. I got a call from the Police at around 1 am to come down and secure my business, so I rolled in and found the place slightly burgled. I had to find a contractor to come in and put some plywood up to cover the huge opening where the 4' x8' glass used to be.
As it turns out, it was a burglary team, and they didn't have any intention of burglarizing my shop- just yet. I suspect the point was to gauge my reaction time, because they came back in a month, this time with the plans to the common area electrical phone closet...are you starting to see what's coming? They disabled the alarm and phones, kicked a hole through the sheetrock that separated the closet and out shop, took every tool they could lay their hands on, put toothpicks in all the exterior door locks, took manager #1's kid's picture off the wall (hmm...wonder why?), stole the cash can, and placed the empty cash can out in the warehouse. They also stole my old Nextel Phone back when they were brick-sized.
Well, these guys went all over the area burglarizing businesses. The cops could never seem to find them. Eventually someone saw their lookout using a bicycle to cruise around quietly. The cops decided to do the same, and started riding through the local industrial parks on bicycles. Eventually, one of the cops was riding around at 3:00 AM, and rode past a business where the lights were on. He saw a gentleman sitting in the breakroom with his feet up on the table, but no car out front. The cops were waiting for him when he came out, and arrested him.
Manager #2 saw a news blurb on TV about the burglaries and saw one of our businesses stickers on a Nextel battery in the background. He drove an hour away against the instructions of Manager #1, identified a few pieces of our property and recovered them.
A year or so later I was clearing some junk out of our mezzanine, and found the burglars had left behind a rolled up copy of our alarm diagram behind. The alarm was installed by a company that manager #1 had selected.