Any -racing or not- game in PS4 needs Plus sub in order to be used online.
GTS,Pcars 2,NFS,"whatever" title.
So bringing up the "free" update car list is a weak argument (to justify the Plus sub) in this situation as much as talking about racing games offered in other platforms.
If we go down that road "GTS has free cars" vs "Forza/PCars has a better car/track list" then fans from any title would have ways to make their "favorite" look like a better deal one way or another.
"Forza has x 4 car list"...
but
"GTS does not have paid DLC"
but
"Forza has a more complete list to begin with..."
but.....
Since every game in PS4,needs a Plus in order to be used online when you want to buy and play online for one year any PS4 title,it cost is:
Game+Plus price for a year.
Lets say I can buy GTS for 30 Euros -hard copy used or not-.If I want to play online that means I need to spend 30+59,99 (Plus)=89,99 euros for the one year.Those 59,99 euros would give me access to online play in all other titles I'll buy.So the more games I buy,the "less" money I pay for online gaming (per game),making online gaming cost less when I actually pay more money in total to SONY (if that makes sense).
Example:
GTS (only) :30+59,99=89,99 for one game
GTS + Destiny 2 (random game and price example) : 30+30+59,99=119,99 or 59,89 per game.
So,more games added to my collection means "less" money I spend for online gaming -per game-.
In case of comparing just one game with any other (similar title) in other platforms then PS4 games could actually be a lot more expensive than what people may think.
Example:
GTS (30 dollars) + PS plus for one year=89,99 (for our US friends)
How much is the money for the basic iRacing (the most expensive sim racing game in PC) for one year?
66 dollars for the basic one year pachage.
So in reality,if I want to make any online PS4 title a "value for money title" I need to do 2 things:
a)Buy at least 2 titles and
b)After their price is reduced (aka not when those games are released).
Because If I want to buy GTS (or Pcars 2 or whatever title) "standard" edition and play one year (online) only that title,with the first day release price tag :
69,99 +59,99= 129,98 for one year.
At this moment the standard edition of GTS in PS store is actually 59,99 -Europe-.So the price of the game (digital) -with online use- is 119,98 Euros for one year, almost double the price of one year iRacing basic sub -the "most expensive" sim in the PC market-.
So atm if I go to the Ps store and want to get GTS with online access (one year) I have to pay 119,98 Euro for the standard edition.
Pcars 2 would cost me 129,98 euros atm.
Dirt 4 would cost me 129,98 atm.
A.Corsa would cost me 72,98 atm.
If I buy all 4 titles:
59,99+69,99+69,99+12,99+59,99=272,95 or 54,59 per game -online cost-.
All these are without any paid DLC added.
So,the more money I spend to SONY PS4 games,the less expessive those games are.
What can I get if I spend the same amount of money on PC racing titles for one year online gaming atm?
150 to iRacing (with DCL money spend in the game)
29,99 for rFactor 2
27,99 for A.Corsa
59,99 for Pcars 2
and still have 5 euros less money spend for 1 year of online racing titles-plus I would not need to add more money to play rFactor,AC or Pcars 2 online after that first year-.
So in order to actually make any valid "value for money" argument for any racing title in PS4 you need to :
A) Buy more that one game (in order to make Ps Plus price drop per game) and
B)wait for a price drop at the same time.
Now,I know that with Plus you get free games but those are sometimes games you may not like or play so I dont bring it up here.Especially if you are a sim/racing game fan and you only play that kind of titles,the "extra/free" games mean nothing to you (90% of the time).
We know that sim racing is kinda an expensive hobby.The more you spend,the better experience you have:VP,rigs,wheels and so on.
But as far as the titles (compared to each other) then we have to dig a little more further to make a solid "value for price" arguments than just "car/track" list -for online racing that is at least-.
And "sim" racing do not actually come cheap in consoles as many people think.Now,does that kind of money actually gets people the experience that worth that price tag?
We could go on for months/years talking about that.....
As far as OP's idea:If you want "free" online racing then you should have not picked up PS4 in the first place.PS4 cost less money than a gaming PC but online gaming is not free and it has a price tag of 59,99 euros per year (atm).