Greetings, individuals.
Recently, we acquired an X3 M40i (285kw variant) and on our journey back home, I was driving the S4 (the 354hp 500nm petrol model, not the TDI version) while my wife was in the X3. As we accelerated from 10mph to around 70mph, we saw that the X3 exhibited a little faster acceleration before we decelerated.
I am seeking assistance from someone with a more technical and physics-oriented mindset, with superior knowledge compared to my own, in order to comprehend the underlying reasons behind the phenomenon of seeing an object or event as quicker, despite its objective lack of increased velocity. I acknowledge the observation that diesel engines tend to provide a perception of increased speed due to their higher torque output, which is available at lower engine speeds. However, the two vehicles under discussion possess equal torque figures, with the X3 being just 150-170kg heavier.
When operating the X3, there is a discernible decrease in speed compared to the B9 S4, which exhibits a notable increase in initial acceleration upon engaging the boost. I have not had the opportunity to do a direct comparative analysis between the M340i and the S4, both of which are sedans of comparable form.
Upon analysing the Dyno charts, it is evident that the EA839 engine in the S4 attains its maximum torque output at 1370rpm, while the B58TU engine in the X3 achieves peak torque at 1900rpm. Considering the S4's ability to reach peak torque around 500-600rpm earlier than the X3, it raises the question of whether this time advantage significantly contributes to the perception of increased speed in the S4. Although the torque of both vehicles is the same, the X3 M40i exhibits an additional 25 kW of power.
For those with prior experience operating sport utility vehicles (SUVs), including ourselves who are novices in this regard, does the vehicle's weight also contribute to the perceived speed of the car?
Thank you for any contributions.
