An outside air temperature readout of 41.2 degrees Celsius means that the day of our AC test was indeed hot. It began with us driving a Tata Nexon and Mahindra XUV 3XO to a location on the outskirts of Mumbai, parking them, and essentially letting them roast under the Indian summer sun. It wasn’t long before the temperature inside these compact SUVs went past 50 degrees Celsius! Before we see what exactly happened once the AC was turned on, here’s how we conducted the test.
Autocar India’s testing methodology
In preparation for the test, each car is parked under direct sunlight for two hours with its engine switched off and windows rolled up. Sunroof shades are kept closed, but rear window shades are rolled away. Once a car is ‘soaked’, a two-member team enters the vehicle quickly to minimise loss of heat – our job is to simulate a worst case scenario. Each car is rigged with sophisticated test gear provided by Zen Microsystems. Five thermocouple sensors read ambient temperature, cabin temperature, vent temperature (it captures how cold the air is), front-seat temperature (measured near the driver's ear) and rear-seat temperature (measured at the rear centre armrest).
Front vents are directed at the driver's face, while rear vents are aimed at the rear-seat centre occupant. As the car is switched on, climate control is set to recirculation mode, maximum blower speed and the lowest possible temperature. Temperature readings are recorded after one minute of idling, and then after an interval of every five minutes (up until 15 minutes) of driving over a fixed route at 50-60kph. A final reading is taken after another minute of idling.
A key disclaimer: Ambient temperatures and humidity have a big bearing on cooling performance. Hence, our results are from vehicles tested on the same day, and these may vary for you based on your location and ambient conditions.
Tata Nexon vs Mahindra XUV 3XO AC test
1. Tata Nexon front and rear AC performance
Tata Nexon cabin temperature during AC tests (in degrees Celsius) | ||
Parameters | Front seat temperature | Rear seat temperature |
Start | 51.2 | 51.2 |
End of 1 min idle | 39.2 | 41.7 |
5 min driving | 31.2 | 33 |
10 min driving | 30.7 | 31.7 |
15 min driving | 30.3 | 30.2 |
End of 1 min idle | 31.7 | 31.5 |
As we began this stress test, the temperature inside the Tata Nexon was 51.2 degrees Celsius (both at the front and rear). With the engine turned on and the AC blasting cold air, the temperature up front fell by 12 degrees Celsius in the first minute. Over the next 5 minutes of driving about, the mercury dipped by another 8 degrees Celsius. By the time our tests concluded, the front of the Nexon’s cabin saw the temperature drop by 19.5 degrees Celsius.
The temperature at the rear of the Nexon’s cabin started out at 51.2 degrees Celsius (same as with the front). It then trailed behind the temperature recorded at the front of the cabin, before settling at a readout that was slightly lower than that up front. However, the temperature readout at the rear of the Nexon’s cabin was 19.7 degrees cooler than when we started. The Tata Nexon gets an ‘Xpress Cool’ function for its climate control system. While it maximises cooling and lowers the driver’s window to get rid of trapped heat in the cabin, we left it untouched to adhere to our standardised test protocol. Regardless, the Nexon’s blower distributed the AC’s cold air around the cabin effectively.
2. Mahindra XUV 3XO front and rear AC performance
Mahindra XUV 3XO cabin temperature during AC tests (in degrees Celsius) | ||
Parameters | Front seat temperature | Rear seat temperature |
Start | 50.7 | 49.5 |
End of 1 min idle | 44.5 | 41.7 |
5 min driving | 36.5 | 36 |
10 min driving | 35.2 | 35 |
15 min driving | 32.8 | 31.5 |
End of 1 min idle | 35.5 | 34.2 |
The Mahindra XUV 3XO gets a dual-zone automatic climate control system and rear AC vents – the former being unique to the 3XO in the segment. As we started its engine and turned on the AC, the temperature at the front of the cabin dropped by 6.2 degrees Celsius in a minute’s time. At the end of the first 5 minutes of driving, the temperature up front fell by a further 8 degrees Celsius. Over the next 11 minutes, as we came to the end of our AC stress test, the temperature at the front of the XUV 3XO’s cabin was 15.2 degrees lower than at the onset.
The rear of the XUV 3XO’s cabin measured 1.2 degrees Celsius lower than at the front when we started. With the dual-zone climate control running at its highest setting, the temperature at the back fell by 7.8 degrees Celsius in the first minute. Over the course of the next 5 minutes of driving, the mercury dropped by another 5.7 degrees Celsius. The lowest temperature recorded of the XUV 3XO’s cabin was 31.5 degrees Celsius by the end of 15 minutes of driving, at the rear of its cabin. This indicates a drop of 18 degrees Celsius since the start of our AC stress test of the Mahindra SUV. Both compact SUVs feature a panoramic sunroof.
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