I can see where you are coming from but all those flashy things in life, while appealing to some aren't really important. Your kids might not realise that yet and can be swayed for a bit.
You're not going to magically be able to outspend him and you shouldn't try. Buying affection rarely works, especially if it doesn't come with care and love between the big "demonstrations". It can leave you feeling like you are just a commodity, paid to go away until they have a use for you.
Which would you prefer?
Someone who only supports you when you do what they want you to. Who will belittle your aspirations and tell lies and manipulate your feelings. BUT they will buy you fancy stuff occasionally to make you feel better.
OR someone who is constantly looking out for you and cheering you on. Makes sure they show you that you are important to them and loved. Who is ready to listen to your dreams and tell you that you are going to be able to attain them. Who might not have a lot of money but makes sure you are taken care of and gets you little treats when they can. Who cares about you when you are sad and always a shoulder to cry on when things go wrong. Who will never be able to get you a dream car but will show you how to be your best self and never give up, so one day you can be proud of yourself for attaining it. know who I want in my life and prefer.
It's also best not to get into a "which person is best" fight if you can. If he gives her a car, it doesn't diminish the steadfast love you give her, it just means she's got a car. Let him do the best of him that he can and be glad for her when he does something nice and be there for her for the many many times he will fall short. You are going to have a few years before she's full standing on her own feet and she's going to need both of you and find value in the things both of you provide for her, both emotionally and financially. As long as they are safe and not being abused by your ex and family, there's things that will benefit your kids by having contact.