How do you finance a new (used) car purchase?

I know most of the country will whack it on car finance, PCP, personal loan or other death debt product but those in this sub that don't drive round in absolute few hundred quid bangers how do you plan for needing a new car?

Single car family so it's essential the one we have is reliable, our car is a 64 plate Ford Kuga with ~73k miles, fine at the moment but we're aware it won't last forever. Also worth mentioning we get it serviced regularly to try and make it last.

Should we be putting a few hundred pounds a month away so that we have money to buy a car in 2,3,4 years time? Doing this would take away from how much we're able to put in our S&S ISA in the short term but I guess would be cheaper than financing the car when we need a new one? What do you do if you know you're going to need to spend £8-12k on a car at some point?