The Hindu : Metro Plus Hyderabad / Wheels : Start, stop, save

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Wednesday, Jul 15, 2009

Metro Plus Hyderabad

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Start, stop, save

Mahindra Scorpio Hybrid now comes with the Start/Stop system that improves fuel efficiency, writes Hormazd Sorabjee

Photos: Ashley Baxter

Innovative touch The Start/Stop system or micro hybrid, which costs a fraction, makes much more sense in the Indian context

Mahindra’s Start/Stop system developed jointly by Mahindra and Bosch is so good, it won Autocar’s Innovation of the Year award for 2009. After first testing this system — dubbed by Mahindra as the Micro Hybrid in the Bolero — last year, we found no discernible improvement in fuel economy. However, we knew this clever yet uncomplicated system had the potential to deliver significant fuel savings with a little bit of fine-tuning, and this time around, it’s been fitted to Mahindra’s flagship Scorpio.

The Start/Stop system functions through a very simple process. When the car is stationary and idling (in neutral with no foot on the clutch), the engine waits for a few seconds before switching off automatically. Press the clutch and before you can select first gear, the engine fires up and you are ready to go. The logic is clear cut — switch off the engine and you burn no fuel — ask any cab driver!

The hardware is pretty compact and sits deep inside the engine bay. All it consists of is a beefed-up starter motor to cope with the stress of frequent starting, an uprated alternator and a stronger battery to handle the extra electrical load. The crankshaft sensor sends information to the ECU, which in turn decides when to start or stop the engine.

What’s crucial here is the interval between selecting neutral when stationary and the engine shutting down. In the Bolero we previously tested, Mahindra had set an agonising 10-second delay which proved too long even during rush-hour traffic as cars constantly inched forward; so remaining completely stationary for more than 10 seconds is not that frequent. Okay, clogged intersections and major junctions can keep you waiting for several minutes, but more often, you are ready to move almost immediately after the engine shuts down. This really defeats the purpose of the Start/Stop system. To register an improvement in fuel economy, the engine should idle less, and hence needs to shut off more frequently. We felt the idling time shoud be reduced to five seconds, which is exactly what Mahindra has now done. But has it made a difference? We tested the new Scorpio Start/Stop system for over 1,000km in Mumbai city, with the system switched on and off (there’s a button on the dash which disables the Start/Stop function, and the Scorpio runs normally) to get a precise comparison.

In Start/Stop mode, the Scorpio returned a frugal 11.5kpl, a near one kpl improvement (0.9 to be precise) in normal mode. That’s a pretty impressive figure for a piece of kit that costs just around Rs 4,000. The biggest flaw in this system is that the air-con stops working when the engine switches off. Even the music system resets every time you restart the engine. Hybrid cars such as the Civic Hybrid don’t have such problems as the additional run off on electric motor is powered by a bank of batteries.

The Start/Stop system or micro hybrid which costs a fraction, makes much more sense in the Indian context as compared to the pricing of the wallet-crunching Civic Hybrid. Now, if only they can find a way to keep the air-con running.