I’ve been playing the demo for a while and just bought the game yesterday. Thought I’d share some engines that I designed. They are the same engine, one is just turbo charged for a luxury or sports edition of a vehicle.
i1291.photobucket.com/albums/b541/zed211288003/Automation/AutomationLauncher2013-06-0712-51-41-72_zpsada25c31.jpg
i1291.photobucket.com/albums/b541/zed211288003/Automation/AutomationLauncher2013-06-0712-51-23-02_zpsfaf4de58.jpg
Not bad… good man hours and costs… the MTBF is a bit dodgy tho 
i would reduce the stroke and increase the bore and also fill in that fuel octane gap by improving the compression. Apart from that its a good engine 
Nice job small luxury car though to have a 2.4l engine maybe if you preorder you could make a 6cyl engine I think they’re really smooth
they are 
My dads always had a v8 or 8 cyl until now he has a 4 cyl and from experiance from other people’s cars 6cyl are the smoothest.
I6s are very smooth (but not V6s!), but V12s are the smoothest.
Can’t wait till v12s I just need a pc now.
A good challenge is also to keep the efficiency within check! I personally managed to make a 2.0L I4 Turbo that produced 150 hp with a 30.5% efficiency! Also, you seem to be running on very expensive fuel (93 AKI) which is not what a 2.0L I4 would normally run on. Think about what kind of gas you would put in a Jetta or something like that that uses a 2.0L I4. Regular or premium unleaded makes a lot more sense. Last things, emissions are pretty high, take a look at that.
Edit: I saw that only the high-end turbo engine runs on 93 AKI but that’s still quite a lot. I’d personally try regular for the NA and premium for the turbo.