Breakdown on truck brands' max speeds

[Dotpoint]

Hello, I was going to drive today on ETS2MP, but game updated and I had to make something else instead. And here we are!

In Euro Truck Simulator 2, trucks' speed is influenced by two things. Engine, which power accelerates and sustains the speed; and Transmission, which determines the rotations' ratio between axle(s) and the engine.

The important thing is: Better engine does not make your truck's top speed higher. It may make the load easier to pull or it might make you achieve the top speed, but there is a hard limit of how fast the engine can rotate the transmission.

Let me explain.

Transmission

In ETS2, transmission has two variables, which determine its speed: Gear Ratio and Differential. I will use a simplified transmission of Engine -> Gearbox -> Drive Shaft -> Differential -> Axle(s).

Gearbox transmits engines rotation to drive shaft, changing the ratio of rotations between engine and drive shaft, depending on situation when driving. Gear Ratio is how many rotations the engine makes to rotate one time the drive shaft.
Opticruise GRS895 (Scania R first transmission) has gear ratio of 11,32 (1st gear) to 1,00 (12th gear). It means that when at 1st gear and engine is running 1000 RPM, drive shaft is rotating 1000 RPM / 11.32 = 88,34 RPM. In the 12th gear the drive shaft would be rotating at 1000 RPM, because the ratio is exactly 1,00.

Differential is a mechanism that allowes the tyres to rotate at different speeds when turning, it also causes some loss of speed. In the game, differential is displayed by a number. Number means how many rotations the drive shaft makes to rotate the axle and the wheels one time. Bigger number means slower top speed, but better torque, for heavier loads.
Opticruise GRS895 has differential of 2,71. When we are driving at 12th gear and the engine is rotating at 1000 RPM, drive shaft is rotating at the same speed. If drive shaft is rotating at 1000 RPM, axle will rotate one time every 2,71 rotations of the drive shaft, we get 1000 RPM / 2,71 = 369,00 RPM. With this number, we can make comparisons.

Brands' speeds comparison

Some brands have the same transmissions, and even if they have a different name, they have the same stats. Retarder does not affect the top speed.

All values are calculated at 1000 RPM and at highest gear. No in-game driving comparison was made.

As of 1.27.2.8:

DAF XF105 / Euro 6 (for some reason, first gearboxes were different for DAF trucks)

• ZF 12AS2330TD (105): 371,75 RPM
  
• ZF 12AS2330TD (Euro 6): 378,79 RPM
  
• ZF 12AS2530TO: 416,25 RPM
  
• Allison 4500: 381,72 RPM

Iveco Stralis / Hi-Way

• ZF 12AS2330TD: 378,79 RPM
  
• ZF 12AS2530TO: 416,25 RPM
  
• Allison 4500: 381,72 RPM

MAN TGX

• ZF 12AS2330TD: 378,79 RPM
  
• ZF 12AS3140TO: 416,25 RPM
  
• Allison 4500: 381,72 RPM

Mercedes-Benz Actros / New Actros

• PowerShift G281-12: 366,30 RPM
  
• PowerShift G330-12: 379,74 RPM
  
• Allison 4500: 381,72 RPM
  
• PowerShift G280-16: 300,06 RPM

Renault Magnum / Premium

• Optidriver AT2412D: 378,79 RPM
  
• Optidriver ATO2612D: 416,25 RPM
  
• Allison 4500: 381,72 RPM

Scania R / Streamline

• OptiCruise GRS 895: 369,00 RPM
  
• OptiCruise GRSO 925: 405,84 RPM
  
• Allison 4500: 381,72 RPM
  
• OptiCruise GRSO 925+: 315,66 RPM

Volvo FH16 2009 / FH16 2012

• I-Shift AT2812D: 378,79 RPM
  
• I-Shift ATO3512D: 416,25 RPM
  
• Allison 4500: 381,72 RPM
  
• I-Shift ATO3512F + ASO-ULC: 377,07 RPM

Conclution

To sum it all up, there is little difference between brands. But now we can end the big question: Which truck can go fastest?

It is Volvo. And DAF, Iveco, MAN and Renault. These trucks have the fastest transmissions and have highest top speeds, if you are using level 10 transmissions.

Of course engine power is a big factor, and the power trio of Volvo, Scania and MAN do feel as fast as each other. Mercedes-Benz in other hand has unusually short ratios and you can feel how the engine is running at high RPM, but you can't go as fast as you can with your Volvo.

For the heaviest loads, Volvo is still the best. The level 16 heavy-load-gearbox, is pretty fast compared to MB and Scania, so try it out.

Hopefully this helps you out and clears some things out. Leave your comment, if this helped out. I might update this as the game goes, depending how much attention this gets.

Happy trucking!

[irishmafia2020]

Cool info... unfortunately I've already comitted to Iveco in my own campaign... is there anyway to change trucks? I really should have gone with a Volvo, and now you've confirmed my gut feeling that it was the better make of truck in the game...

[Dotpoint]

As long as you have found a Volvo truck dealer, there is nothing that prevents you from changing truck brands. The Favourite Truck -selection just gives you the first job and later reveals nearest brand dealer.

[Mr. Nice]

While what you say is true for the theoretical transmission limit for top speed (assuming equal rev limit for all trucks, which seems to be about right in game), there is also the theoretical engine limit for top speed, where the speed at which the resistant forces (aerodynamic + rolling essentially, accounting for "transmission losses"). Of course, to achieve this you need a gear where the rpm for max power is achieved at this speed also. But to hit the transmission limit, power generated at max rpm needs to equal or exceed the resistant forces at this speed also. Either way, you can't isolate just the gear ratios or just the bhp of the engine as defining top speed.
The GRSO 925 is still doing less then 200rpm at ~105mph for example, so that it is slightly shorter then the longest gear box of some other manufacturers doesn't mean much.
Btw, I've modded my GRSO 925+ to have the same final differential ratio as the GRSO 925. As even the comments point out in the files, the gear ratios of the two boxes are identical outside of the 925+ gaining two crawler gears, so seems silly to saddle the 925+ with a shorter differential. If anything, with the two crawler gears it could get away with a taller differential. I believe in real life customers can mix and match gear boxes and final differentials to some extent.

[FiendKing04]

Nice, appreciate you taking the time to go in-depth with the comparisons.