Quite number of people in google+'s Asphalt 8 communities said that R&D was quite doable within 15 days. But what you have to realised is that many of people in that communities were mostly pro-ish player. Of course, they will never say such thing. But what I see is they mostly achieve within top 1,000 (even 300 or 500) in TLE(Time-Limited Event) . If I'm not mistaken, about a hundred thousand or two hundred thousand(in Android) people are playing that TLE. So top 1,000 out of 200,000+ players. Was I wrong to call it pro-ish player?
Not only that, you have to maxed out and almost pro-ish car to win the car. And other hard part is every 3 hours to refill the key to play.
You can see the maxed out cost from here , as you can see 2.5 million credits needed. And you need number of S class cards, Mid-Tech and V10 engine cards. And more credits for pro upgrade.
It is so hard that quite number of people saying that they spent 1,000+ tokens to win the car and couldn't sleep because every 3 hours to play the R&D .
So am I have chance to win? I think not. So I planned to not play it at first. But R&D is there so I tried it with just first upgrade(cheapest upgrade part) and it was quite doable, I felt. So I only played it for rewards and not spending any credits and pro cards.
So what I'd like to suggest is playing it only for rewards. So don't upgrade it and have a good sleep. And play it only when you want to play it.
I only spent first upgrade--because it's always cheap, so total 38,450 credits. Other two upgrade was from R&D rewards--I tried to spent my other S Class upgrade but it wasn't possible. And zero pro upgrade.
And I played it only during the day. And two or three days, I played only 2 or 3 times only.
But as you can see, I am in Test 15.
But I think this test is my final stage (or maybe one or two more test) with those upgrades because many times(more than half of times), I failed to finish first which is main objective.
I can't catch up beginning part and then they crashed in front of me so I couldn't get out of from it. And then those ai cars are so fast that one or two mistakes made me loose the first position and then I couldn't catch up.
I am using the boosters when I have remains from the TLE.
If you do it like me, you can get quite bunch of tokens, S Class cards and a few Mid-Tech Cards.
So you can play it in the mood of relax. Not pressure to win the car.
It's more enjoyable for me.
p.s. I did that test for 4+ days. And I passed that test but I can't beat that ai in test 16 so that's end of it for me.
Anyway, I'm trying to do in Windows now and I did upgrade it to 1-3-1-1. But I don't think I can pass test 16 but hopefully it wasn't that hard in test 15.