My dd recently passed her driving test. We have put her on the insurance of my car to use evenings and weekends.
I assumed her social life would carry on as normal and she would use the car instead of us giving her lifts, making our lives easier and not costing us any more money.
She doesn't have a job and plans to go to uni next year, so we have done all this with no expectation of her paying for any of it. DH and I argued about it and I compromised on getting a car for her to putting her on my insurance.
She has taken to going out a lot more often and going much further afield. So for example, instead of getting a pizza with friends in town a mile away, she will do a 25 mile round trip to the next town. Or if she goes to the cinema, she will take 3 friends and drop them all home, so doing 30 miles instead of 2!
DH and I are arguing about this. I don't really want her taking a car load out every time she drives (she never drives it alone!) because of the safety issues, she's statistically much more likely to have an accident with other teens in the car but also the fuel and mileage and the fact that I am having to hoover it out more! I am paying for it all and am starting to resent it but DH says I'm being petty and I should be pleased she's getting out more.