Is auto-dimming IRVM really needed in cars of all shapes and sizes

Mahindra offers auto-dimming IRVM only in the XUV400 and XUV 3XO. Incidentally, these two are the shortest cars from Mahindra and this is no coincidence.

BHPian Geta recently shared this with other enthusiasts.

Being a satisfied XUV500 owner for the last 5 years, I was always perplexed to read the posts in Team-BHP every single time Mahindra launched a new car. As usual, the cars will have great engines, 6-7 airbags, excellent safety ratings, cutting edge technology like level 2 ADAS, panoramic sunroof, mouthwatering prices etc., but still, in practically every few pages someone will spring up and say "no auto-dimming IRVMs???! Horrible cost-cutting!". I had seen at least 25 such posts in the various Mahindra threads (Thar, XUV700, ScorpioN, XUV3XO, Thar Roxx) in the last 4-5 years, so much that I started wondering "Am I missing something which is very obvious to others?"

Frankly, I have driven more than 60K kilometers in my XUV500 and my ownership experience has been excellent. More than a third of my drive has been after sunset and I have never felt any necessity for any auto-dimming IRVM all these years. I might occasionally flip the IRVM manually when there is a glare, maybe 3-4 times a month. That's it. Nothing more than that.

For some reason, I had to take my wife's car out (Hyundai Grand i10 Nios) consecutively on three nights and the reality dawned on me. Many a time in city traffic, when a bus/truck comes within 15 feet with a high beam on, when you end up looking at the IRVM, it really causes severe eye strain. There is eye strain even with smaller vehicles but more so with buses/trucks as their headlamps are at the same level as the IRVM (about 4 feet from the ground).

When I went back and did a little Google search, it was clear that vehicle headlamps can not be lower than 24 inches from ground level and can not be higher than 54 inches (4.5 feet) from ground level. Most Mahindra cars have a roof height of 175 cms (XUV700) to 186 cm (Scorpio N, Thar, Thar Roxx). These vehicles have their IRVMS typically 4 inches below the roof. Hence the height of IRVMs is generally about 5'6" to 5'10" from ground level, which is at least 30 cms above the highest headlamps in buses/trucks (4'6").

Moreover, the shoulder line of the rear hatch of XUV700, Scorpio N, Thar and Thar Roxx are all taller than 4'6" (i.e, the glass portion starts only above 4'6") thereby effectively cutting the glare from the headlamps of the buses/trucks behind in close range.

On the contrary, in smaller vehicles, like Hyundai Nios (roof height 152 cms), the rear hatch shoulder ends at about 3'6" from the ground. The IRVMs too are placed exactly at 4'6" from the ground level, thereby ending up directly reflecting the lights from the headlamps behind.

Case in point: Auto-dimming IRVMs are offered only in 2 cars from the Mahindra stable: XUV400 and XUV3XO. Incidentally, these two are the shortest cars from Mahindra stable (height 165cms). This is no coincidence.

So, for most cars, if the IRVMs are positioned at a height of 5'6" or higher, I genuinely feel that there is no absolute requirement for auto-dimming IRVMs. The product development team at Mahindra really deserve to be appreciated for their clarity and understanding!

P.S: I hope Pratap Bose fanboys don't give him the credit for this.

Here's what BHPian Bit had to say about the matter:

As much as I pay my respect for the extensive research you have done, the only reason Mahindra has auto IRVM in only 400 and 3XO is that their other cars were either launched before auto IRVM became a mainstream feature to bother about (Xuv 500, Scorpio N, Thar etc) or launched during/post covid times when electronics were scarce and sourcing of auto IRVM was kinda resource intensive.

Once both of these things settled, ie. cars launching well after the pandemic and its associated shortage was completely over (Read: 2024 onwards) they started giving auto IRVM in every car, regardless of its height, size, or stance. Case in point: Recently launched Thar Roxx with auto IRVM.

Please note my reply is not to debate with your theory of auto IRVM being useful or not (I shall cover it in a separate comment) but just to clarify that Mahindra’s decision of not including auto IRVM in their yesteryear’s cars was not some well planned, carefully thought move - it was just their lack of ability / attention to procure it.

Here's what BHPian Chetan_Rao had to say about the matter:

I flip it once to dim mode to drive at nighttime and flip it back when parking end-of-day. Don't need another electronic gizmo to save me that effort.

What I'd like more are dimmable ORVMs, to mitigate the nutcases in our country tailgating with high beams, and flashing furiously to express their anger in Morse code.

Here's what BHPian vvs29 had to say about the matter:

I have experienced auto-dimming IRVMs only on my Fronx. All other cars I drove at night had only manual dimming. And the Fronx's IRVM does not help. It does dim but it is nowhere enough to stop the blinding lights from affecting me. Maybe it is designed to keep some visibility. I much prefer the manual ones which are at least effective. I'll survive the inconvenience of having to flip it twice a day. So I'm in the bucket who wants to actively avoid having an auto-dimming IRVM.

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