Unless you are buying a super rare car or one with a history or famous previous owner then cars are not going to be good investments.
I think it depends on the marque. For example Porsche GT3, GT2, Turbo and anything with the coveted RS (Renn Sport) are going through the roof. I have had to have my Turbo re-valued almost each year over the 5yr ownership as prices keep climbing.
Apart from a big chunk of spend when I first bought it, it has had annual services and any advisories sorted at each service.
It has had 4 new tyres which are consumables on this car and were replaced due to age despite having 5mm tread on the rear 295's as Porsche recommend no more than 6 yrs age on tyres irrespective of amount of tread - so its 3mm tread or 6 yrs age whichever comes first.
Taking lifetime ownership costs exc. Insurance, I am still in pocket if i came to sell.
I bought at the bottom of the depreciation curve, chose the right model (Mezger engined Turbo with 6 speed manual gearbox), factory X50 option, low mileage (22k at purchase) and full Main Dealer OPC history.
Choose well, and it can be investment potential - but that was not the primary reason for purchase.