Easy one Mr Squashman, just tell her that it makes the car more economical and will pay for itself after a year, then after that you will be saving moneywhich you could be spending on her....or your car!
Ahem!
Sundance
The following user(s) said Thank You: sworkscooper
Trouble is, have you heard the saying "Elephants never forget" and believe me she would not only log the date that I made the statement but would remember it for several years to come!!