AIBU to resist replacing our old cars despite my mother-in-law's comments?

I think MIL has made a valid point even if it's not her place to make it. You've got plenty of money but chosing to buy old cars that will have issues and having to borrow from your parents is madness.

We traded in our workhorse 11yo car last year. I brought it from new with the bit of inheritance I got from my grandparents, no issues until about 9.5 years in and then I probably spent more fixing it than I had in the previous years in total but that's a car we'd had for years. I wouldn't deliberately buy an old car with 100k miles, especially not with young children. You were lucky to only wait an hour. Even if you don't want a new car there's probably a decent middle ground if you took some out of your savings or looked at a loan/leasing.

Seems strange to have to borrow money from parents when you have £100k in investments. Why so little in liquid savings?

Older cars are fine if you are happy to accept that things will go wrong. But your saving seems skewed. Save money for car replacement, household items, holidays etc before investing. It doesn't seem fair to borrow from your parents when you have money. How are you about to pay them back if you only have 2 thousand in accessible savings?

I put YABU because I think breakdowns put you and your family at risk. Also because once a car goes over 100k miles the chances of things going wrong go up and up and they can become a money pit. You don't need to buy a brand new car but you could (and IMO should) use some of that money to buy a much lower mileage car. But all that said you are adults, how you spend your money is your decision. If I was your parents though I'd be telling you off too. I was in a shitty old car once whilst heavily pregnant, and it developed a water leak which one time I was driving to the hospital for a scan became catastrophic, the engine had no water, and it cut out in the middle lane of the motorway. It was terrifying. I wouldn't risk that again ever.

It sounds like your husband is considering a new car. So it's a discussion for the two of you to have.
I personally would feel uneasy driving cars with over 100k on the clock that have broken down on the motorway. I'd think they were unreliable after that and wonder what was going to go wrong next.

While cars are an excellent way to waste money, you do need something safe and reliable to get you from A to B. Stranded on a hard shoulder is a dangerous situation to end up in.

Sometimes you do have to recognise that instead of saving for a rainy day, it is drizzling right now. Getting older, high milage cars is risky because you don't know how they've been treated, what's been worn through and how much life is in them. Some cars were just made more reliably than others, some have been driven more gently with better maintainance.

I think it depends if your cars are actually dangerous.

Although in general I am with you. Brits seem to be quite out of touch with what they will need to save for the future, and when they do save often it is just cash in the bank or a buy to let, rather than the stock market which generally offers much better returns.

Why are you borrowing money from your parents and driving your child around in unreliable cars if you have over 100k sat in investments? It doesn’t make sense.

I drive an old car that has needed some work on it lately but the difference is I don’t have a child who could potentially be stranded and I can’t afford a new car without going into debt.

I see your mil poverty and pretty much agree with her.
Sure, new cars can also break down but im guessing less likely to compared to a new one.

I was really pleased when I bought a new car on 5 year finance once, I paid it off in 2.5 years and kept the car for 10. Around the 10 year mark it started to go wrong, initially small things like needed oil frequently, then other things, I cant remember what now. Dh had been nagging at me to change for years and pointed out that I do a lot of motorway driving and did I really want to chance it going wrong when I was in rush hour on the M62. I got a new car and heard that my old car's engine gave up the ghost two weeks later! Since then I change every two or three years. I did look after the old car and have it serviced regularly but as most cars age things are more likely to go wrong.
Reliability and safety are the two most important things for me However I dont want to be worrying what im going to paying for next.

1. Her opinion doesn't matter; this is entirely your decision unless she is paying for it. I'd tell her that directly.

2. Stop telling your MIL how much money you have in the bank/investments.

It’s a difficult one. We generally buy a car that is a couple of years old and hang on to it for 8 or 9 years. Our last car was a BMW and we kept it too long. In the last year we had it we spent about £1000 keeping it running “just to make it last another year” before our retirement. Unfortunately diesel started leaking into the wiring loom which would have costs about £2.2 k to fix. Not worth it and the car had to be scrapped. We got virtually nothing for it to put towards our next car. Very poor/unlucky decision for us to hold on and keep repairing it. We plan to change this new car in 5 years.

Make the decisions which work best for you and your family. It’s nothing to do with your MIL. But make those decisions with your eyes wide open.

Op, I'd be getting a new car tbh.
You can get amazing lease deals too if you'd consider that?

A lot rather than a car with over 100k miles on it.

Why does she know you have “all that money”?
keep your finances to your selves and ignore her nonsense. It’s non of her business.

Is the campervan overpriced and under used? I can see her frustration if the entire fleet is just not feeling fit for purpose.
Saving are there for rainy days but just because it's raining you don't need a new thing.

Perhaps pause the investments for a couple of years and plan to replace your cars after saving up for them?

It's recommended that you keep a few months in accessible cash before investing so something else to look at?

I’ve always kept cars to well over 100,000 miles and never broken down. Diesel engines will go for a long way from decent brands. Sounds like you’ve been unlucky. The belt should have been replaced at a particular mileage though, mine needs to be done at 80,000 miles and my current car is on 65,000 miles so you should have kept an eye on that or your mechanic should have told you it needed doing. Unless it was just bad luck that a new one snapped?

You need to get that engine light looked at. YABU if you don't. We have had old cars. We airways keep them till they cost more than they're worth to fix.

Garage owner here,we are finding that newer cars are braking down far more theses days,they have so many ridiculous electrical systems that aren’t really needed,plus the modern engines are rubbish compared to older cars.I advise my customers to buy cars 6 to 10 years old according to their budget that have proper service history ie with receipts not just random stamps in a book.Get it fully checked out at a local garage by a reputable mechanic who is old enough to know what they talking about(experience is vital) French and Italian cars are cheaper for a reason(electrical faults manly)Ask all family and friends if anyone is changing their car just because they want a newer one rather than because it’s playing up !. I would say 50% plus cars are being sold because of underlying issues (I see it all the time,i tell people what’s wrong with their car and they say oh ill trade it in then) Now it’s someone else’s problem ! So if you have a reliable order car get it serviced regularly and keep it as long as possible.Better the devil you know really.Good luck

What kind of cars do you have?
Toyotas just go on and on - they are workhorses! 100K is nothing on the clock for the cars. We got rid of a Toyota last year for a newer car. It was 12 years old and 130k on the clock. This was a mistake I now regret.

Why does your MIL know about your finances?

My Toyota corolla has 212000 km on it
It's 10 years old.
It broke down in January and cost me 300 euro.
After playing 300 euro I'm keeping it for another year at least.
It passed its national testing in May.

That 300 euro would bearly pay for a new car for a month.

Any car can break down.
Keep driving the cars until you get an expensive repair bill

Have your cars serviced regularly. Ask your mechanic to watch out for a low km reliable second hand car, no more than three years old if you want to swap out one car for a more reliable one.

Speak to your accountant about what is the most profitable way to make use of your savings, if your objective is wealth creation.

I don't think driving new cars is more financially savvy than driving reliable, not too old second hand cars.

Stop telling your MIL about your car ordeals.

It is literally none of her business. Is she an acknowledged expert on cars?

Any car can break down. That's why you have recovery services. And engine warning lights are meant to come on. That's why they exist, and usually only indicate a maintenance issue.

If you were having different issues every month, then it might be time to look for a new vehicle but one problem in each is not a valid concern.

I agree with your MiL. You need to prioritise safety and the here and now over money for retirement long into the future. You need a reliable car on the motorway.