Mar 24, 2017 06:42 PM
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The overall rating score is a combination of how a car scores on performance, comfort and convenience, safety and security and mileage on a scale of 100. The overall rating factors in the weight age on each parameter depending on the car type, price segment it comes in. The higher the overall score the better it is. The scoring on each of the parameters such as performance, comfort and convenience, safety and security and mileage is an aggregate score of all the factors related to particular parameters respectively
The overall measure of performance of a car is the consolidation of a number of factors that influence performance. This score is a relative score based on the aggregation of scores on various parameters including top speed, braking, acceleration, types of brakes, ground clearance of the car, drive type(front-wheel drive, rear-wheel drive or all-wheel drive). All these parameters have been given relative weight ages. We have assigned 25 percent weight age to Performance to compute the overall rating score.
The overall measure of how comfortable & convenient a car depends on the features that it offers, as well as taking into account our scientific tests on how much noise, vibration, and harshness enter the cabin, how comfortable the seats are and how effective the suspension is. The Comfort and Convenience rating take into account seating capacity, wheelbase, types of seats, interior lighting, climate control system, power windows, locking systems, seat adjustments, audio infotainment system among other factors. We have assigned 40 percent weight age to Comfort & Convenience to compute the overall rating score.
Buyers are now placing greater priority on safety and security in a car. Our scoring for safety and security on cars includes the number of safety-related features that the car offers such as anti-lock braking systems(ABS), electronic brake-force distribution(EBD), immobilizer Anti-theft alarm, traction control, fog lamps, a number of airbags, safety locks etc. Each of these is given a weight age depending on their importance in overall price segment and relative commonality of these features in that segment. We have assigned 20 percent weight age to Safety & Security to compute the overall rating score.
Our rating for mileage of each car is based on the claimed fuel efficiency of the car as certified by ARAI for city driving. The score is relative to how other cars in the same segment fare on fuel efficiency. Diesel cars are obviously more fuel efficient than petrol cars, and we have Taken that in the weightage on the fuel efficiency scores. Diesel and Petrol variants are taken separately to calculate the mileage rating. We have assigned 15 percent weightage to Mileage to compute the overall rating score.
One of the key measures of comfort in a car is the amount of noise and vibration you can perceive in the cabin. Cars that are noisy lead to driver fatigue in the long run. Our NVH test comprises high-sensitivity microphones set up at standardized locations in the cabin to measure the decibel levels of engine noise, wind noise and road noise that a driver and passenger will feel. We also use highly sensitive vibration sensors on the steering, seat, gear lever and floor to gauge the frequency level of vibrations in Hertz getting transmitted into the cabin. The data collected from the various sensors is compiled into an absolute score for noise and vibration, to simplify the readings. This is further split into five easy-to-read bands in which all cars fall. Harshness is a combined factor of perceived noise and vibration – which leads to the perception of a car being rough or smooth.
Seats are one of the most critical components in a car when it comes to driver and passenger comfort. The design of the seat matters a lot in determining how comfortable the occupants will be after a long journey. To measure seat comfort we use a highly specialized seat pressure mapping sensor that is a membrane spread over the seat, which has tiny one-square centimeter sensors over it. These measure the pressure the seat exerts on a driver or passenger’s body in the form of a heat map, where the more number of red squares visible, the more uncomfortable the seat. Similarly, the suspension of the car also plays a big role in occupant comfort. To determine how efficient the suspension is in soaking up bumps the car is subjected to a standardized bump test, where the vertical movement of the car is measured as it goes over a speed breaker, to determine how much of that its occupants will feel.
A measure of steering effort will determine how easy or difficult it is to drive the car and whether or not a driver will get tired driving it. Similarly, we also track the effort required to press the clutch in a manual transmission car, which will tell you how comfortable or not you will be driving this car in bumper-to-bumper traffic conditions. Steering effort is measured using a steering torque and angle sensor, which looks like another steering wheel, placed on top of the regular steering wheel of the vehicle. It measures the torque required in Nm to turn the steering at standstill and for a slow U-turn. Clutch effort, measured in KgF, is carried out using a pedal force sensor that is placed on the clutch pedal to determine how much force is needed to keep pressing and releasing the pedal.
How fast a vehicle accelerates from standstill to a 100 kmph is one factor in its performance. This is dependent on the power of the car, the weight of the car and the gearing. To measure acceleration we use an inertial measurement unit coupled with a GPS and measure how fast it gets from 0-100 kmph. Similar tests are conducted for braking as well, to see how fast it gets from 100 kmph to 0 and in what distance. Brakes are a key part of safety equipment in the car and the quicker a car can stop, the safer it is. The size and type of brakes and whether or not it has an anti-lock braking system play a key role here. Since there are discrepancies that can creep in under varied test conditions and cars, the exact time taken in these tests has been averaged into an absolute score based on multiple readings, and divided into bands relative to all other cars.
