Tata Motors launched the Harrier earlier this year, and the SUV is selling like hot cakes. Tata Motors does not offer an all wheel drive layout with the Harrier even as an option, and customers have to make do with a front wheel drive layout. What Tata does offer on the Harrier though are multiple drive modes: normal, wet and rough. These modes are meant to vary torque between the two front wheels, helping the Tata Harrier get out of a sticky situation if it ever finds itself in one. The SUV was recently put through a roller test to demonstrate how effectively the rough road mode works. The entire process was documented video, showing the Harrier in action on the roller, in all three modes. Here, check it out.
As the video indicates, the Harrier struggles to get out of the roller in normal mode, both with ESP on and off. ESP works by braking one/more wheels losing grip and bringing the vehicle back in directional control. In a low grip situation such as a roller, braking a wheel won’t really be effective. Instead, torque has to be varied, giving one wheel extra torque to pull the vehicle out of the roller (low grip situation). This is the reason why turning ESP on and off in normal mode does not really make a difference. Eventually, additional throttle input to help the Harrier power its way out of the roller is what gets the SUV to clear the obstacle.
Next, we have the wet mode, a mode that limits power to the wheels so that there is no loss in control in the wet due to excess wheel spin or too much power overwhelming the tyres. Even in this mode, the Harrier takes a while to get out of the roller, and additional throttle input to increase torque and let the SUV power itself out of the roller is what helps.
Finally, the rough road mode is deployed, and as the video indicates, the Harrier – near instantly – gets out of the roller, with little drama. Clearly, rough road mode is a lot more effective than both normal and wet modes in giving the Harrier enough grip to get off the roller with minimal effort. This happens by channeling torque to the wheel on firmer ground with higher grip levels (right wheel). By diverting all the torque to the right wheel, the Harrier easily gets out of the roller. This test demonstrates how the rough mode works on the SUV, and that it can be quite effective in situations that demand distribution of torque to one wheel.
What needs to be clearly understood though is that an all wheel drive system is a lot more effective than the Harrier’s rough road mode. This is because an all wheel drive system can vary torque across all four wheels, giving the vehicle a lot more grip than a two wheel drive system ever can, rough road mode or otherwise. So, while the front wheel driven Harrier with the rough mode is better than a regular front wheel driven SUV without such a mode, it can’t really be a proper off roader. At best, it can handle some mildly slippery surfaces.
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