Derived out of the speed graph on the main straight

The vehicles straight line acceleration is mainly determined by the vehicle's weight, engine power and drag.

Since the vehicle's weight is easily measured, one can by comparing the speed graphs of the model and real car get a good estimate of both the engine power as well as the vehicle drag.

One should keep in mind that engine power works from the point where full throttle can be transfered to the road. This contrary to drag which mainly has an influence at higher speeds, mainly influencing the highest speed the vehicle reaches on the straight.

The example above gives a clear impression how engine power and drag combine. The speed graphs of real car and model are shown for the 'best' power and drag values as well as an example where the engine power of the model is reduced by 5% and the drag of the vehicle is reduced by 7%.

As can be seen the speed at the end of the straight is the same, in both cases. The difference occurs after full power is aplied (first arrow) till the point where the drag gets a big influence (second arrow).

In the figures on the right, examples are shown of 5% more or less engine power, as well as 7% more or less aerodynamic drag. Out of the speed graphs can clearly be seen that in case of the engine power, the speed graphs start to diverge way earlier compared to when the aerodynamic drag is changed (shown by the arrows).