[Driving80kph]

Same in my Baleno. I can alternate between fresh air and recirc as I need in Auto mode.

[mostlynerd]

It’s important to read the manual guys. It clearly says that you will still retain the auto mode but the setting you changed manually will come into force. They call it semi automatic mode. The word Auto disappears from the display.

Semi-automatic Operation
Making any manual selection causes the word ‘AUTO’ in the display to turn off and overridden setting is displayed. System will remain in semi-automatic mode till ‘AUTO’ is pressed again.

The importance of the user manual is lost in this day and age and we all have pages of discussion on these things. RTFM.

[arulpeem]

Originally Posted by abhi7013

Most cars don't allow recirculation when they are set to auto. There must be a well thought rationale behind this if such a setting is followed by most manufacturers.
Maybe since its 'auto', it might switch to re-circulation mode after a set time so that the cabin gets filled with fresh air first? Just guessing, never tried!

The level of CO2 will keep increasing. In an enclosed space the limit is about 1000 Part Per Million.
Even in an air conditioned office which has more volume of air per person I have seen the values shooting upto 1800 ppm when the fresh air intake is reduced or stopped. The technicians do this for the same reason as we use re circulation, to speed up the cooling. This happens typically about an hour two after the office is occupied.
Imaging in a much smaller space the amount the CO2 level after an hour of riding without the re circulation.

One can google of the ill effects of increased levels of CO2.

[amalji]

Originally Posted by arulpeem

The level of CO2 will keep increasing. In an enclosed space the limit is about 1000 Part Per Million.
Even in an air conditioned office which has more volume of air per person I have seen the values shooting upto 1800 ppm when the fresh air intake is reduced or stopped. The technicians do this for the same reason as we use re circulation, to speed up the cooling. This happens typically about an hour two after the office is occupied.
Imaging in a much smaller space the amount the CO2 level after an hour of riding without the re circulation.

Good points. These are things that i am always a bit hyper about. In fact, you can feel the tiredness on long drives, if the cabin is full and you have ac switched on in recirculation mode for long.

I found an interesting link in the Lexus faq where it says that even in recirculation mode, there's 10% fresh air which gets in. I'm not sure whether it's always the case or whether there's a sensor which does it based on requirement. And I'm not sure whether all manufacturers does it the same way as well.

This is the link - https://lexus2.custhelp.com/app/answ...till-enter-the

And this is what it says

When the system is set on Recirculation Mode, does "fresh air" still enter the vehicle?
Yes; The air conditioning system is designed to allow up to approximately 10 percent of the air coming from the air vents to be fresh air from the outside. The exact amount of fresh air entering the vehicle on recirculation mode will vary.

If the A/C system is turned on in the AUTO mode, then the A/C ECU switches the air intake ducting between "fresh," "fresh and recirculation mix" or "recirculation" according to the required outlet air temperature that the ECU calculates. This calculation is based on the following:

• Temperature Dialed in with the Control Knob
• The Interior Air Temperature
• The Operating Conditions

On a different note, i have seen the recirculation mode go off automatically at times on my Innova crysta as well. I've still not figured out a pattern as to when it goes off though.

[Ferruccio]

Guys a car is not hermetically sealed in 'Recirculate' mode. All modern vehicles have air extractors, usually located beneath the rear bumpers. Even the flap that closes the air vent will still let some air in, which is why when there is a strong smell outside (particular roads in Mumbai come to mind) you will be able to smell it inside the car. You may wish to try it in a static vehicle with an agarbatti outside. Remember that it is far more pronounced in a moving vehicle.

[locusjag]

Originally Posted by Ferruccio

Guys a car is not hermetically sealed in 'Recirculate' mode. All modern vehicles have air extractors, usually located beneath the rear bumpers. Even the flap that closes the air vent will still let some air in, which is why when there is a strong smell outside (particular roads in Mumbai come to mind) you will be able to smell it inside the car. You may wish to try it in a static vehicle with an agarbatti outside. Remember that it is far more pronounced in a moving vehicle.

I agree. In my TUV 300 as well as in my A-Star, smoke from roadside fires does makes its way in despite the cars' being in recirculate mode. There is definitely some leeway to the outside world even in that mode.

[Vmv]

The Big come back !

HEXA Safari Edition

Thank you TATA , You are listening Now

[navpreet318]

I just read a comment on Instagram. Hexa Safari Edition- Sexa!!! Hahaha
I frankly am very very intrigued by this new development. Are we talking about Auto with AWD or 4WD. I have a fixation of Auto with 4WD. I just hope it gets fulfilled in a decently priced package. Else the big ones will need to be spent.

[vibbs]

Originally Posted by Vmv

The Big come back !

HEXA Safari Edition

Thank you TATA , You are listening Now

Wow. That's a great one.
Tata has always had the knack of getting such kickass advertisements. Sadly these are of more sporadic nature and we don't see it translate into a regular feature.

Plus it is heartening to see Hexa still being in the mix of things as far as Tata is concerned.

[abhi7013]

Originally Posted by Vmv

The Big come back !

HEXA Safari Edition

Thank you TATA , You are listening Now

Am guessing that this is just an edition that they will be showcasing at the auto expo and will not be available for mainstream sales. They are yet to make it BS6 compliant. Might just be one of their prototype designs which does not see the light of day.
Or, and i wish this is true, they are close in launching the BS6 Varicor and this would be one of the trims/kits available when Hexa comes back in future. Only time will tell.

[sugam]

Originally Posted by abhi7013

Am guessing that this is just an edition that they will be showcasing at the auto expo and will not be available for mainstream sales. They are yet to make it BS6 compliant. Might just be one of their prototype designs which does not see the light of day.
Or, and i wish this is true, they are close in launching the BS6 Varicor and this would be one of the trims/kits available when Hexa comes back in future. Only time will tell.

Would they be advertising on social media if it were only a prototype? My gut says otherwise.

[padmrajravi]

Hexa is now the only AWD vehicle in the TML portfolio. I think they are trying to position Hexa as a single 4x4 manual option model at the same levels of Gravitas top-end model. They can then push everyone who wants a seven-seater towards Gravitas and place Hexa AWD as a halo product which is there only for namesake and made to order basis. Once Harrier twins come with 4x4 after a couple of years, they can pull down Hexa. Maybe in 2023.

[amalji]

Originally Posted by Ferruccio

Guys a car is not hermetically sealed in 'Recirculate' mode. All modern vehicles have air extractors, usually located beneath the rear bumpers. Even the flap that closes the air vent will still let some air in, which is why when there is a strong smell outside (particular roads in Mumbai come to mind) you will be able to smell it inside the car. You may wish to try it in a static vehicle with an agarbatti outside. Remember that it is far more pronounced in a moving vehicle.

The car is not hermetically sealed. But, based on whether the car is in recirculation or fresh air mode or whether the windows are open, there is a huge difference in the CO2 build up inside the cabin and high CO2 level directly translates to tiredness and lose of alertness. You can feel this in real for long drives especially when the cabin is fully occupied.

There is a good paper on this - Modeling CO2 Concentrations in Vehicle Cabin

Some points from that paper.

• Recirculation mode decreases the ultra fine particle concentration levels ( upto 85% reduction in particle concentration ), but increases the CO2 concentration. Vice versa for the fresh air mode.
• To put the CO2 build up effects in perspective, the CO2 concentrations rise to 4500 ppm in 10 minutes with 3 passengers onboard!
• Occupational Safety and Health Administration (OSHA) has established 5000 ppm as the Permissible Exposure Limit (PEL) of CO2 for 8 hour

There are 2 examples given in that paper as to how some manufacturers tackle that.

BMW invented the automatic air recirculation (AAC) system [12]. The AAC
system relies on a fast responding gas sensor to detect high concentrations of gaseous pollutants on roadways. Then the AAC system quickly and automatically closes off air intake from outside and temporarily recirculates the air in the cabin. It reduces passengers' exposure to high concentrations of air
pollutants. It does it in a way cabin air temperature is not changed and fog is not formed in the windshield. This is an on/off recirculation control triggered by a gas sensor. The effectiveness of their system relies on the fast response of the detecting sensor and the actuator.

Second, Grady et al. [9] proposed fractional continuous recirculation as opposed to full recirculation. This is to suppress increase of the CO2 concentration while lowering particle pollutant concentrations in cabin air. They showed a small change of the recirculation door angle can effectively suppress increase of the cabin CO2 concentration. By controlling the amount of fresh air under different ventilation conditions they could demonstrate that benefits of air recirculation could be utilized while suppressing the increase of CO2 concentrations.

Interesting graph which shows the CO2 build up in recirculation mode with time.

[hexamaniac]

Originally Posted by padmrajravi

Hexa is now the only AWD vehicle in the TML portfolio. I think they are trying to position Hexa as a single 4x4 manual option model at the same levels of Gravitas top-end model. They can then push everyone who wants a seven-seater towards Gravitas and place Hexa AWD as a halo product which is there only for namesake and made to order basis. Once Harrier twins come with 4x4 after a couple of years, they can pull down Hexa. Maybe in 2023.

yes , i would think its a clever fusion of the Safari & Hexa , the missing 4x4 of the Harrier packed into the new Hexa , really hope TML learns from past mistakes & have done some serious refining to keep up with ever increasing competition

[Anuruddhs]

Good to see Hexa back in game, based on various reports I was also thinking such a great product will die so early. If Tata would have stopped Hexa just after 3 years this would have been my last Tata car. If you are not confident that product you are buying will be supported well for next 5-10 years you loose confidence in brand. By law they have to support for certain time but that support eventually is not that great in most of the cases.