They will both be fully useless for any kind of actual racing right now. PD's insistence on using higher fuel consumption makes the F1 useless right now. There will be races where you can technically take the car, but they will be seal clubbing events with minimal payout. There will be no fun races for the F1.
I don't have the 917K, but like the rest of the cars from that era, I'm sure it'll be serviceable but not really any better than a number of modern cars that you'll be able to get for far less money.
Both of the cars will be purely collector items. If you can't get both, choose the one that you want to collect the most. I'm in the same boat and I'll be choosing the F1 this time around.
Have you used the F1? It's one of the best road cars in the game, with only the F50 being slightly quicker in my testing (like 1/2sec slower at pretty much every track I've ran them and it's all down to the F50 being more planted even when power is added and weight is removed)
F1 is great for Sarthe WTC 700, and it's one of the more "fun" cars to drive, imo. Takes some time to get used to but can easily win at Sardegna WTC 800 with a roughly 750pp setup, all downforce bolt-on's from GT Auto applied. What's great about it in these races is you can run it at FM6 to save gas but due to the limited downforce and high HP/torque you can still reach top speeds well above the opponents. So they can out-corner you, but you've got the acceleration and top speed to nullify this advantage.
At Sarthe it's a 2/3 stop depending on how everything shakes-out (whether you get rain 2x, when you overtake the leader, whether you game the race and play defense to have the timer run out a few hundred meters before the end of the 7th lap)
At Sardegna it's usually 2 stops, 3 if I need to up the fuel consumption for any reason. Certainly not as easy as using the F1 GTR Long Tail or CLK-LM, but when you've run these races so many times you gotta do something to shake it up.
With that said, I'm not saying it's exactly worth the price. However, unlike nearly every other 20mil-ish car it has the ability to enter and win 2 of the 3 most profitable races, so it can earn its keep. Could prob fit into Tokyo but it would be a nightmare with all the rain... I've used it more than any other LCD sans the F1 Long Tail and CLK-LM and plan to buy a second one when it pops up so that I can tinker with weight reduction, etc. It's personal preference of course, but the F1 is one of the best cars in the game imo.
Edit: I should say it WAS amongst the best cars in the game in 1.13. I've barely played since 1.15 so it is possible this is no longer true. I have noticed the CLK-LM is quicker in 1.15 than it was in 1.13 by as much as 2sec at Sardegna, so something was tweaked (could just be the transmission no longer being part of PP calculation) Anyway, I'll jump in and run it at these events to make sure they didn't break it. I would genuinely feel bad if someone bought it on my recommendation if it has been altered for the worse with the latest update.
Update: The car feels a little different to me, but it's probably just in my head. All I've really driven in this game over the last 3 weeks is the Tomahawk and Gr. 1 so I think it was just weird not having at least 800 pounds of front downforce. That said the brakes do feel weaker than I remember, though a swap to carbon-ceramic cleared that issue up. Ran Sardegna 2x on hard, first time I had to pit 3x and took 2nd place, second race I managed 6 laps before needing to pit so I did it on 2 stops for a 4sec win (good race). Also ran it on normal, 2-stopper, and I swear the AI is tougher on normal difficulty than on hard. Had to wring every last pony out by switching to FM1 for the final 1/2 of the last lap. Still only managed maybe a 10 meter lead at finish. Most fun I've had in the game in months! It's not the best road car for this race; the F50 runs quicker (it has rear diffuser option so better cornering) and I'm sure the Porsche GT1 would be a little quicker with the right setup (again, more downforce options) but the F1 is still quite capable and Im positive once Praiano, Exeter, or one of the other top tuners has a crack at it the car will only get better.
This was on Race hards, no ballast, all power upgrades but with power limiter set to 95 to lower the power-band in the rev range, and ECU set a few clicks down to give around 630hp (for better fuel economy) close to stock suspension (softened the rear a bit) and the only assist was the brake zone since I was switching between brakes. PP was like 732 or something like that.
I still plan to buy a second since it can be wide-bodied and there are quite a few permanent engine upgrades available. No weight-reduction though, unfortunately, but at a hair over 2500lb it's far from being a pig to begin with. I stand by my recommendation for it if you can afford it, doubly so if you're an F1 fanatic. It's far from the easiest car to drive, but with some throttle control and practice it is very fast and is just "slippery" enough to keep you on your toes (in a good way)
