Only a few are a lot more expensive.
Let's be clear about the level of difference between the games.
The most expensive cars in GT1 are 500,000 credits (or 50,000,000 if you're running the JP version). Those are the special models and there are 5 (?). The next most expensive cars are the Astons starting at 164,000cr, and it all gets cheaper from there.
http://www.gamefaqs.com/ps/197468-gran-turismo/faqs/3911
Gran Turismo 6 has 6 cars that cost 20 million credits. It has 280 cars that cost at least 500,000 credits, by my count. That's within spitting distance of a quarter of the cars costing as much or more than the most expensive cars in GT1.
It's not a few that are more expensive. There are lots.
Yeah like the races are a lot shorter and still pay very well.
As an average, almost certainly they are given that GT6 doesn't include endurance races. If you're comparing Sunday Cup to Sunday Cup, I don't see it having changed much at all.
It really is not a problem to get lots of credits in a short while playing in GT mode. In fact I can easily rack up more credits in GT6 than I could in GT4 in a given period of time and that includes the price for selling the prize cars in GT4.
What's the most efficient way for you to earn money offine? How long would it take you to earn 20 million credits to buy one of the most expensive cars in GT6?
Then we can compare that to GT1, where running Megaspeed 7 times gives you enough cash to buy a 500,000 car (with a bit left over). Megaspeed consists of three races of two laps each. At those speeds a lap is about a minute, so six minutes of actual track time to complete the series. Let's give some time spent for messing around in menus, and call it an even hour to earn 500,000 credits.
(Yes, that guy messes around a lot tuning his car. It doesn't take half an hour to complete the series.)
Can you earn 20 million credits in GT6 in an hour? That's the difference. GT1 really wasn't that shy about giving you enough cash to buy stuff. That changed a lot when the prices of cars went up in GT5 and 6.
In GT6 1.01 a 20 million credit car was damn near 40 hours of playing the most efficient races, before there were seasonals and online bonus and Red Bull. That's not right. It's less than that now, and I'll be interested to see how much less. But I'll be very, very surprised if it's anything like what GT1 allowed.
With GT, its a similar story. If you didn't have to work at all for the Lamborghini Miura, the feeling of actually owning one would be completely unsatisfactory. Do you see what i am getting at here?
Which is why the credit system is a good thing.
But there's a balance to be struck between making someone work hard enough for something that it feels like they've earned it, and making it a chore. Making someone save for an hour or two for that special car
does make it feel more special. Making someone save for 10 hours, or 20 hours, or 40 hours does not. There are severely diminishing returns on this.
There's also the problem that because GT doesn't allow test drives of anything bar a few cars, and reselling is severely penalised, if someone spends a lot of money and doesn't like the car they're going to be cheesed off. If they've spent an hour or two, they'll be miffed but they'll get over it. If that's 40 hours of gameplay wasted, they're going to throw their controller at their TV.
I don't think that there's sufficient benefit to making someone "work" for more than a couple of hours for any one car. I think that's enough, and that any more than that isn't really adding to any feeling of reward that they get out of it. That's just my experience, from watching myself and people around me play.
I think it would improve GT if it had a flatter pricing structure, and you could afford a cheap everday car every 10-20 minutes, or an expensive car (say, modern supercar or racecar) every hour, or a super rare showpiece car (like the 20M cars now) every couple of hours. That would strike me as a reasonable time investment for the reward, and with so many cars in the game people are still going to put in hundreds of hours to be able to access a significant portion of them.
It isn't that a credit system is bad. It's that this particular credit system is poorly designed to achieve what it's supposed to, namely making people feel like they earned a car without making it feel like work.