Unfortunately this is all too common a scenario in the 318is household.....
You can't just get it and tell her you've just fitted a grip to your 1000D, however, if there is a positive in it for her she might be a bit more flexible;
Here you go love, have my 1000D
Would you like some new shoes
I've tidied the house, hoovered up, done the washing up and made you dinner
Let me go and run a nice hot bath for you
I thought we could spend some time with your parents this weekend
Then leave it a couple of days and mention the 1DIV again, by which time she would have been sufficiently weakened by your kindness!
NB - Also throw in there a limited time cashback offer as well so you can get a bit more off but you need to order it now.