Hello.
I’ve done some testing of engine size and body morphing, and I have some questions/suggestion.
I’ve also added some of my bugs and wishes in this topic. I hope that You won’t throw it to other category 
1. Engines
- All engines in one family are the same size. It shouldn’t be like this, because even in one family 1.6 should be smaller than 2.0.
- Sometimes ago you had flywheel slider. Why did You delete it? Will there is a chance to get it back? I think that flywheel slider is the great opportunity to balance between smoothness and responsiveness. It is one of engine’s basics, so it shouldn’t complicate gameplay so much. And then You can add some other stuff like dual mass flywheel.
2. Morphing
I’ve been testing 00Minivan01 morphing influence on economy, passenger space and cargo volume.
- Number of seats does not influence in passenger space and cargo volume.
- After morphing an aerodynamic “nose” on the front bumper, passengers gain additional space. And this should only add engine space. Another option is to move all engine chamber to the front of the car, but nothing like this happens.
- Resizing arches changes passenger space and cargo volume. WTF?!
- Adding wide arches means adding additional drag, but sometimes it causes better fuel economy.
- Morphing an aerodynamic “nose” on the front bumper, means worse fuel economy. Flat front bumper that should be less aerodynamics, in game means better fuel economy. That aerodynamic nose is probably made of lead, because adds additional 50kg to the car. To compare my panzer off road front bumper weight less than 30kg
- Changing angle of windshield and hood does not affect on economy (but You probably know that)
3. Vehicles and engines list
- Could You add “see all” button on engine family selection list during car building. It is very needed because, I have so many families, that they all doesn’t appear on the list. And even when they appear, it is almost impossible to find proper family if there is no sorting. This “see all” button could work like in previous version of game: shows Engine sandbox list where we can sort it by every column (Of course I know that sorting is temporarily disabled).
- Could You add additional filtering level in model and engine filtering? I mean “Brand” level. Why? Usually player make more than one brand in the game. And when I own VW group, I don’t need see all VWs, Skodas, Seats, etc., when I’m want to manage Porsche. And when I want to search engine to my Porsche I’m not interested in seeing 1.0 MPI Engines.
- When expanding/collapsing family members in sandbox, the list get back to beginning. It is really enjoying when You try to expand six families from the middle of long list.
4. Errors
- In some point of the game (usually when clicking new engine family during car building) it starts crazy lagging. Mouse clicking and cursor moving is delayed about 1 second; and sound is “shattered”. To fix it I call windows manager list and get back to game.
- When You using in one car two different engine families game getting crazy, and shows variant of different family that have been chosen.
I’m apologies if some of topics were posted before, but I couldn’t find satisficed answers. And many people asking the same questions means that they really cares about Your (our) game 
Cheers