Either I gently suggest we put a nappy on for a nap and she gets furiously worked up because (a) she doesn't want a nappy on, and (b) she really really doesn't want a nap. . No point wrestling one on her - she'd be too worked up to sleep.
Or, she goes to sleep in the car / pushchair and I lift her into bed. Fine. But when I try and put a nappy on her asleep she wakes up and is furious and won't go back to (much needed) sleep.
I think she does need one because there's always a wee in nap-time nappy when she wakes.