Can anyone tell me how safety statistics for soaring compares with
statistics for driving automobiles?

If you are wondering if flying is more dangerous than driving the
answer is an unequivicable yes. How much more dangerous is hard to
determine (do you drive drunk?). Most of us have to drive, whereas
flying for most is recreational. If you want to reduce your requests
find the toughest, most demanding instructor you can (I assume you are
a student). Demand extra instruction, not just the minimum required
for the ticket.

It is informative to read the accident reports at the NTSB web site.
Most glider accidents are pilot error, and most fatal accidents are
stall-spin. You can train for this (see above). It is absolutely
imperative that you take the correct action for each and every
emergency. I recommend getting some power instruction even if you have
no intention on getting a power license. You can get alot of landing
practice this way and you will appreciate the issues faced by your tow
pilot.