Solved

How do you get good starts?

My driver Ruiz is in the most developed car and should be good stat wise yet still struggles in getting a decent start. In almost 3 or 4 consecutive races he loses about 5 positions in the opening 3 laps. Is there any way to get better starts?

Having less fuel aboard helps a lot

In general, I agree with Slo Bro. Less fuel can help a lot but sometimes there are strange things in this game...

Australia, I was first of the soft with 11 laps..if I remember well, no one had less fuel than me.. the one behind me had 15 laps of fuel.
It was the best situation for me but...the guy with 15 laps started well, he overtook me and I lost 10 positions in the first lap.. 

Europe, I started second with 14 laps of fuel. The guy on pole position had 11 laps. It was also raining. The perfect situation for him. I overtook him at the first corner...

So, in conclusion, fuel can help, but the start is a lot random in my opinion..

In Europe, in the first corner, the second almost always overtakes the first

I think it's a bug

I must have been having some bad luck recently. It kinda struck me as a bizarre occurrence since I had the fastest acceleration in the league

Push level as well I assume
Just my opinion

Push lever 5 at the start, in my opinion, is a no brainier. At least until the tire temp indicator starts to creep up.