MG4 Undertray dip/bulge

[Rolfe]

When the undertray fell off my old Peugeot the garage advice (two separate garages) was to leave it off, it doesn't do anything anyway. But this was a 1998 ICE car.

I expect it was intended to improve aerodynamics.

 

[Kithmo]

Is that a bulge in your undertray? Or are u just happy to see me ?
Sorry, I couldn't resist ?

 

[Emgie 4]

I'd a BMW 320 that developed a leak in crankcase gasket, and after I repaired it I left off the undertray for a while to monitor for any more leaks, needless to say I forgot to replace it and found it in backyard months after selling car - tho I did locate new owner and gave it to him, no idea if he ever put back on.
The point is I noticed zero difference in fuel efficiency (and I do monitor it) or any handling issues, can't comment on crud build up as didn't look too often, but I suspect the undertray's function is minimal for most cars.
Altho I guess range and efficiency becomes a much greater issue where EVs are concerned
Secondly as many before have said if MG put it on the car it should be fit for purpose, and if not - FIX it, no IFS and BUTS about it
IMHO I think the bad PR this single issue is causing, has potential to lose MG more than it would have cost them to fix it day one.
Why can't they see, it's the principal, regardless of cost or purpose of the thing, I'm only glad I didn't have one of the dealers who spouted "shur there all like that"or worse "there supposed to be like that"

 

[Macadoodle]

I think that with ICE cars we simply don't notice small changes, the fuel is just so energy dense.
Also, I wonder if missing a front undertray will have less effect than a rear ?
Air piling up behind the back bumper might result in more of a 'parachute effect' on the car

I just clamped my bulge, so to speak, with a bit of thin aluminium plate I had lying around which flattened it nicely. Shouldn't have to of course but life's too brief to worry about nonsense IMO.

 

[Emgie 4]

I think that with ICE cars we simply don't notice small changes, the fuel is just so energy dense.
Also, I wonder if missing a front undertray will have less effect than a rear ?
Air piling up behind the back bumper might result in more of a 'parachute effect' on the car

I just clamped my bulge, so to speak, with a bit of thin aluminium plate I had lying around which flattened it nicely. Shouldn't have to of course but life's too brief to worry about nonsense IMO.

Granted, altho I literally think my fuel consumption didn't reduce by even 0.1mpg without the tray, but I also think you may be spot on with rear v's front tray affect, I didn't even consider that ?

 

[Ian Key]

I think that with ICE cars we simply don't notice small changes, the fuel is just so energy dense.
Also, I wonder if missing a front undertray will have less effect than a rear ?
Air piling up behind the back bumper might result in more of a 'parachute effect' on the car

I just clamped my bulge, so to speak, with a bit of thin aluminium plate I had lying around which flattened it nicely. Shouldn't have to of course but life's too brief to worry about nonsense IMO.

Did you take a photo of before and after?

 

[Rolfe]

Or even just after, as we have lots of before photos from around the globe!

 

[Macadoodle]

I'll be sure to take a snap next time I have the ramps out ?

 

[Rolfe]

I'm thinking, if it gets to the point where I take the car to my local garage and ask them to fix it, it would be good to have some idea of what works. My tray isn't nearly as bad as some I've seen, but the dealer doesn't seem to me to have made a huge difference.

 

[Nobbyplopps]

Has anybody else with a MG4 my23 got the bulge. On the undertray I mean

 

[siteguru]

Has anybody else with a MG4 my23 got the bulge. On the undertray I mean

Just 2 pages back:

MG4 Undertray dip/bulge

There is some evidence that they have a redesigned tray. I suspect they're using up the dud ones in the hope people won't notice.

www.mgevs.com

 

[Nobbyplopps]

Just 2 pages back:

MG4 Undertray dip/bulge

There is some evidence that they have a redesigned tray. I suspect they're using up the dud ones in the hope people won't notice.

www.mgevs.com

Got it, thank you

 

[tsedge]

Got it, thank you

We don't understand why it isn't addressed on recent cars except to speculate that it is either not economic for MG to change it and/or they don't think it is a major issue.

I do wonder how often it is raised in the "real world" - the only way most people know is through forums and a tiny percentage of MG4 drivers visit forums like these.

 

[Nobbyplopps]

We don't understand why it isn't addressed on recent cars except to speculate that it is either not economic for MG to change it and/or they don't think it is a major issue.

I do wonder how often it is raised in the "real world" - the only way most people know is through forums and a tiny percentage of MG4 drivers visit forums like these.

Could it be that it is thought of as an issue because people mention it in forums like this, and people without the bulge don’t say that they don’t have it?

 

[Emgie 4]

We don't understand why it isn't addressed on recent cars except to speculate that it is either not economic for MG to change it and/or they don't think it is a major issue.

I do wonder how often it is raised in the "real world" - the only way most people know is through forums and a tiny percentage of MG4 drivers visit forums like these.

I'd say your spot on, and maybe a combination of both.

Just curious has anyone done the sums of MGEV forum membership numbers v's cars sold in same region, to see actual%

Another avenue I think where some see issues is YouTube, definitely for reviews but also for problems to look for, I have to confess when I'm thinking of a purchase(car or otherwise) I tend to search for issues and problems not just reviews, but maybe that's the pessimist in me ?

We don't understand why it isn't addressed on recent cars except to speculate that it is either not economic for MG to change it and/or they don't think it is a major issue.

I do wonder how often it is raised in the "real world" - the only way most people know is through forums and a tiny percentage of MG4 drivers visit forums like these.

Also ignorance is bliss, if you've never read it on a forum or heard about bulge elsewhere - and never looked under your car,
You could happily drive away oblivious, probably unaware of slight range impact and crud build up

 

[JonnyG]

Haha, if I had read all the forums before I bought my last two cars I probably would have reconsidered and missed out on two good cars. Admittedly the second one had a few annoying infotainment glitches (Golf Mk 8) but with hindsight I would still buy another.

 

[PristDean]

This morning I had a call from my dealership. They told me a replacement under tray has been delivered and they can fit it on the 24th. As mentioned elsewhere, it's all down to finding a good supportive dealer, one that is large enough to have its own budget and not have to seek authorisation from MG for the slightest thing.

Warped trays may still be appearing as they use up old stock rather than just dump them. Then hope some people just don't notice.

In my view, warps in the under tray can create a detrimental effect on the aerodynamics of the car, in effect increasing the down force at speed and creating drag coupled with the air meeting a solid rear bumper. Resulting in a reduction in the efficiency of the car costing you money, along with road debris potentially collecting on the tray by the motor.

 

[Ian Key]

This morning I had a call my dealership. They told me a replacement under tray has been delivered and they can fit it on the 24th. As mentioned elsewhere, it's all down to finding a good supportive dealer, one that is large enough to have its own budget and not have to seek authorisation from MG for the slightest thing.

Warped trays may still be appearing as they use up old stock rather than just dump them. Then hope some people just don't notice.

In my view, warps in the under tray can create a detrimental effect on the aerodynamics of the car, in effect increasing the down force at speed and creating drag coupled with the air meeting a solid rear bumper. Resulting in a reduction in the efficiency of the car costing you money, along with road debris potentially collecting on the tray by the motor.

Hope it's the updated design and not one of the old stock ones.

 

[PristDean]

Hope it's the updated design and not one of the old stock ones.

I'll post here what I find

 

[Eber]

In my view, warps in the under tray can create a detrimental effect on the aerodynamics of the car, in effect increasing the down force at speed and creating drag coupled with the air meeting a solid rear bumper. Resulting in a reduction in the efficiency of the car costing you money, along with road debris potentially collecting on the tray by the motor.

That's exactly the point. It's very obviously not meant that way so they should rectify it.