I have run secondhand cars for the past 11 years.
The FULL cost - petrol, purchase, insurance, repairs, tax, aa membership etc - is £55/month. Be super generous and add a £25/month "my car broke down and I needed to get a taxi instead fund" (this has happened maybe three times in 11 years), and it's still £80/month.
And my current car still has years left in it, so that average will keep going down. It's my third car.
I do wish people wouldn't keep perpetuating the idea that secondhand cars aren't cheaper than lease cars. I think it scares young people off from dealing with repairs etc in an adult way, selling them the dream that for £200/month (not including petrol), you don't need to worry
Which is cheaper depends entirely on the circumstances. You have been extremely lucky if the full cost of running any car has been only £80 per month! Many people have to spend two to four times that in petrol alone, depending on commute distance. And insurance - my insurance alone increased £30 this year with no change in underlying facts (full NCD discount and never had an accident), so how £80 could cover all car costs including repairs, tax, servicing, insurance, fuel is baffling to me, but lucky you!
I always bought cars roughly 5 years old outright until recently. Over the years I have had to pay out nearly £20k to fix major faults, repair electrics, air conditioning, random warning lights popping up on the dashboard, wheel re-alignment, etc. All for supposedly sensible and reliable, well-made cars. 🤔
I made a spreadsheet and worked out the true costs. Leasing a brand new one with better fuel efficiency, no need to MOT, any faults covered under warranty so not for me to pay for, lower insurance costs... it worked out cheaper to lease a brand new car. So that is what I do now. And even better, the costs are fixed and entirely predictable and spread out, rather than getting slammed with a £2.5k bill unexpectedly because something is wrong with the electrics.