The way I figure if someone buys a gasoline powered car, they've just committed us to 50-100 tons of CO2 emissions. Seems like that is what you want to stop not playing games with fuel taxes.
This is incorrect. Beef takes a ton of food and releases a good bit of greenhouse gases but nowhere near a ton per kg of meat. Here's a study looking at multiple other studies on the CO2 equivalent greenhouse gases per kg of beef. In particular you'll want to look at page 85.
Can you provide some sources for this number? Seems high, and first results from a cursory Google search suggest it's between 14 to 60 kg CO2 per 1 kg of beef.
Although beef and other animal ruminants have always been part of the planet's carbon cycle where carbon sources are kept in balance by carbon sinks. What knocks us out of balance is extracting carbon sources (ancient forests) from underground and burning them rapidly within a century-- much faster than any natural carbon sink can absorb.