No need pay and no obligation but depending on the dealer,
requirement for some is 21/23/27, and generally no pplate allowed.
And for some higher performance cars, want to test drive also
cannot.
"And for some higher performance cars, want to test drive also
cannot."
That one depends on how deep your pockets are 
. For me,
want to test drive Kia also got problem.
Just a bit of advice, don't go in to a showroom feeling like you
owe the salespeople a living. Be nice, but be
firm. If they give you an attitude, don't be afraid to ask
for a different salesperson.
If they all have attitudes, or you just don't feel comfortable
there at all, think of how bad the aftersales could be if the
presales is already so bad.