Help me reduce Fuel Consumption and Improve Top on my Eco Shitbox

I’m trying to build a practical Eco Car to test Fuel Consumption Reduction by reducing Throttle Losses.

What I am doing right now:

2012 Car, all Aluminium Monocoque, like an Audi A-2 (I may try Fibreglass next)
It’s the 2.0m Wheelbase Mini Knockoff with the Wagon Body, FF layout
Double Wishbone Suspension all around.
10 inch Wheels, 125 Width, Maximum Radius, Hard Compound

All Aluminium 250cc 3 Cyl: 50mm Bore, 42.5mm Stroke, Cast Internals, Low Friction.
Compression. 12.0, 5V Head, DOHC
Cam: 65
14.4 Mixture
55 Ignition
Direct EFI Per Cylinder
Performance Intake
91 RON
RPM Limit 12000
12.7mm Exhaust
Long Tubular Exhaust, Hi-Flo CAT, only 1 Baffled Muffler

All Qualities at 8

Result: 25hp at 7100RPM
27NM at 5100
650kg in BeamNG
Top Speed: 90kph in 4th
86 in 5th

Gearbox and Wheels are all Set at 12 Quality

Theoretically this should enable me to get good Fuel Consumption, but I’m only getting 6.2l/100km.
Top Speed is also very low, a 29hp Citroen 2CV already gets 110kph, a Trabant 601 with 23hp would get 100kph Top Speed easily.

I have 2 more HP, am just as light yet slower with pretty high Quality Parts and the Trabant has Wider Tires.

My 38HP NA Version is at 8.0l and 105kph
My 30hp Turbo Version does 96kph and 6.5l/100km

So my Car is loosing a lot of Speed somewhere, and the Engine drinks a lot, far more than I would expect for a Car like mine.

Your engine is way too small and the car too heavy. You cannot compare a 2012 car to a Trabant or 2CV. The former will always wheigh around a ton, the latter around 450-600kg.

Considering the undersized, underpowered engine, it will always struggle to get the car moving, hence the high fuel consumption and low speed.

Also, your quality is way too high, your engineering time and production costs must be nearing supercar levels.

There’s a reason you don’t see econoboxes with 250cc engines on Western markets with Western fuel consumption and emission standards.

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My Car only weighs 600kg, an this is an example in Downsizing to eliminate Throttling losses.

Try with a 500cc (at least) engine.

(And tone down on the unrealistic quality.)


Well, such an Engine would be based off Motorcycles, which tend not to be as sloppily built as Cars. Also: Higher Body Quality is mostly for Panel Gaps, which should be small.
The Smaller Parts also make higher Quality more affordable.

And this is Experimental. I’ll try to find the lowest Practical Quality later.

I guess using a more modern body would reduce drag too, which hampers both fuel consumtion and top speed.

Also, 95 octane is pretty much standard fuel nowadays, change to 95 and raise the compression.

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Well, I tried it with the 2.1m Wheelbase Mini Hatch, Fibre Glass Body and it runs 108kph with a 7 Speed. 613kg in BeamNG, so it’s really light.
I’ll try 125 Tires and make a 95 Octane 25HP Engine, turn down the Cam, Up the Mixture and see where that goes.

The Family is actually good for 75+hp with a Turbo, and would be good for even more, but the Game Limits me to 12000RPM.

I’m gonna try out a completely Hypered Engine.

I have a 38hp 95 Octane Engine already.

And now a 91 RON 38hp, it’s not that Hard, but I have to use 13.8 Micture.

Maybe you should put the export file on your OP so we can download it and see if we can help.

Just listing all the information doesn’t aid in clarifying where you’re going wrong or right!

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I’m new to the Forum, how do I export it here without external (Virus Infected) Clouds?

First, stop with the quality spam. It might make your car heavier than it needs to be (especially in the pannels/chassis tab. Also, lower cams give better fuel economy, by far (but with lower hp, but better torque curve). Also, if you’re producing power at 7,100rpm cut the rpm limit at 7,600ish, there is no reason to be at 12,000 rpm, that most likely affects gearing, thus, top speed and fuel economy.
Extra quality in tires adds a lot of grip, and it will decrease your fuel economy as well, try 0 quality. And although à gearbox with 8 quality diminishes power loses, probably you’re losing fuel economy there as well.

If you’re using DFI, try 15.0:1 fuel mixture. Also, check the fuel efficiency graph, and tune gearing accordingly, ex. if the most efficient point is at 1,800rpm set the gears such that most of the fuel economy calculations are in that range.

Probably the ONLY place where you would put extra quality for better fuel economy and higher speed is in the aero tab.

And stop posting multiple times, just edit your previous posts if you want to add something.

Probably not the point, but check killrob’s YouTube channel, he recently build a city car with an amazing fuel economy, that can give you some tips and ideas.

EDIT: I just realized @myfabi94 you were trying to build a bike engine. I did tried once, a 600cc yamaha engine on a smart body, to futile results. Seems Automation isn’t really made for that.


How to export and share your car with the forum…

1 - Follow this advice

2 - Share the .car file via the upload button on your original OP

3 - ???

4 - PROFIT!!!

Hope this helps!

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I’m gonna try some of the Changes.

I have a modular engine family with inline 3, 4, 5 and 6 cylinder engines - all of them turbocharged and set up about 95% the same. Why am I saying this? Because in a test car (with variants set up 99% the same) they all get nearly the same fuel consumption, regardless whether it’s a 3-pot version or a 6-pot one. So engine size isn’t that important for economy, it’s the setup that matters the most. For such a small car I’d go with a 0.7-1.0 litre engine even, 0.7 for turbocharged, 1.0 for N/A.

I’m a new User, can’t share anything with you guys.

Try maybe with dropbox, mega or google drive.

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a) 1.0L engine so it can get moving
b) LOWER CAM PROFILE. This was my problem for the longest time and I never knew why I got poor fuel economy. Well, this is it.
c) experiment around!

EDIT: aerodynamics are just as important weight BTW, Mini Cooper is light but also a brick in the wind tunnel.

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2.0 Turbo 40% engine maybe can be good.95 octane.

100mpg (=2.35 L/100km). 26.5hp 295cc I3 turbo. No quality sliders.

Key takeaways:

  • choose a body with low drag
  • lower cam profile
  • AFR of 15.0
  • reasonable RPM
  • tune the exhaust for maximum efficiency
  • gearing is important

Eco Test - (11.0 KB) (place this in My Games\Automation\CarSaveImport)

Note: as others have said, you’ll probably want to use larger engines with more low-end torque for anything more than a car purely designed for fuel efficiency.