is this what they are offering?

Time is so bad their engineers have to moonlight at their rival.
(in case you are not aware, Renault and Toyota are 2 different F1 teams)

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I made it past the first interview.
At the second interview, the assistant manager walked me through the facilities. Then met up with the managing director and the manager. They dug out the arithmetic test I did during the first interview, and said that my result wasn't up to standard of engineers there. Then the manager walked me through the facilities again, giving me brief introduction at every lab. Then he handed me back to HR department. I overheard him saying to the HR staff "why this time round so few resumes? 5 or 6 only? Last time cao cao 20, 30 resumes". Next the HR staff was pleased to offer me the position, talked to me about the salary and the benefits and stuff, and asked me to get back to him when I have decided. Then he told me not to be alarmed if I see their recruitment advertisement appearing again for the same position.
I reached home. Called them back to say I am taking up the offer.
Then HR called back, saying the managing director was out-station and they need his approval. The MD would be back one week later and they would call me up again.
More than one week has passed. The company didn't call back.

If you have read carefully the flow of events, you would have spotted enough fishiness.