Tata Explains Why Sierra EV 75 RWD Makes Less Power Than Sierra EV 63

When Tata Motors launched Sierra EV, one specification immediately stood out. Contrary to expectations, the 63 kWh RWD variant develops more power than the larger 75 kWh RWD version. As per the official technical specifications, Sierra EV 63 produces 238 PS (175 kW), while Sierra EV 75 RWD is rated at 209 PS (154 kW).

That’s a difference of 29 PS, or around 12.2%, despite the 75 kWh model being positioned higher in the lineup and commanding a premium of around Rs 1 lakh across comparable variants. Naturally, this raised questions. Why does the larger battery version produce less power?

Responding to our query, Tata Motors explained that the difference is an intentional engineering decision rather than an error in the specification sheet. “Both 65 and 75 kWh batteries are packaged in the same volume. This has been achieved by selecting a higher capacity cell for 75 kWh and moving to C2P architecture. By the virtue of these choices, the larger battery boasts of class-leading 141 Wh/kg packaging efficiency and 8.9 km/kWh energy efficiency delivering an ARAI range of 665 km.”

Tata further explained that fitting a higher-capacity battery within the same physical dimensions required changes to the battery architecture. “While this choice comes with 99 km jump in certified range, it has resulted in marginal drop in operating voltage and hence, rated peak power.” According to the company, this reduction in peak power has little effect on everyday performance because both RWD variants produce the same peak torque of 315 Nm.

Different variants, different priorities

In a follow-up response, Tata Motors clarified that the two RWD variants have been engineered with different customer priorities in mind. According to the company, the 75 kWh RWD variant is aimed at buyers who prioritise maximum driving range. It uses higher energy-density battery cells and Cell-to-Pack (C2P) architecture to achieve an ARAI-certified range of 665 km, which is 99 km higher than the 63 kWh version.

The 63 kWh RWD, on the other hand, has been positioned as the more performance-oriented variant. It produces 238 PS while still delivering a certified range of 565 km. Tata also said that despite the 29 PS difference, both RWD variants generate an identical 315 Nm of torque in Sport Mode. As a result, customers are expected to experience similar responsiveness in city, highway and everyday driving. According to the company, the difference in peak power is likely to be noticeable only during sustained hard acceleration or spirited driving in Sport Mode.

Following Tata’s initial explanation, we asked why, if the lower-power calibration was an intentional engineering decision to maximise efficiency and extend range with minimal impact on real-world performance, the same approach wasn’t also offered on the 63 kWh variant to further improve its driving range. This question remains unanswered.