A burb beater is a common suburban vehicle, stereotypically driven by a Soccer Mom. The term is from the Neal Stephenson book Snow Crash.
Typical examples of burb beaters vary depending on your location, though in almost any country, minivans or station wagons are prime examples. In New Zealand, honda civics or nissan bluebirds would be common examples of burb beaters.
References: Snow Crash, by Neal Stephenson.
I was doing a buck-twenty down the freeway when a burb beater pulled out in front of me.