The first question that springs to mind is 'What exactly does one define as a feature?'.
Well, actually, the first question is 'Do we know everything about the finished game yet?' - because right now we're assuming that course maker isn't in it, along with a bunch of other things - but that doesn't really help.
I'd be almost certain that Yamauchi has not forgotten all the things that were in all the previous games. I'm absolutely positive he hasn't forgotten things like vehicle tuning, used car garage, dynamic weather and time, the Moon and course maker, so we're left with a few possibilities:
1. They're in the game
2. They're not in the game and Yamauchi has overstated
3. They're not considered as 'features'
Let's take dynamic weather. Yamauchi has said that dynamic weather isn't in GT Sport. He's also said:
So the three options are:
1. It's a feature that is in GT Sport and he was wrong to say it isn't.
2. It's a feature that isn't in GT Sport and he was wrong to say it is.
3. It's not considered to be 'a feature'.
Yamauchi isn't prone to lying. He's prone to optimism and excitedly telling people about what's planned to be in the next game (and the one after it), very much in the same way that Peter Molyneux was*, but I've never come across an actual lie. Sure, GT games have missed release dates, and the next game is always 'probably 80% done' and this thing and that thing had to be pared down from the original plan to the final product (course maker, for example, was 100km x 100km, then 50km x 50km, then released at 10km maximum track length), but never 'this is in my game' when it patently wasn't.
This makes me wonder what is and isn't considered to be a feature. Ultimately, I think it's something that could stand some clarification before anyone leaps in with 'he's straight up lying'.
We may have some more interview opportunities before the game is released, and if we're able, we'll put these questions to him.
*I've heard stories from those who have worked with both, and they share a characteristic of being super-excited about what they're doing to the point of accidentally telling journalists what they're trying to get into the next game rather than talking about the current game that the journalists are there to see. Molyneux was legendary for it, and the publishers he worked for were perpetually in damage limitation mode because he was revealing things that were not only years down the line but might not even make the cut because they were years down the line. This may be why Yamauchi always has a Sony handler or three at any event where he might speak to journalists, and Translator-san may act as another layer of protection; this is also why it was great when he came to speak to me, on his own and in English, about my MX-5!