MG4 wheel swap efficiency hit tested

[Brettus]

Sorry if this was posted anywhere else, I couldn’t see it anywhere obvious but I’m hardly infallible.

Headline results right there.
Full video

I’m kinda surprised it’s that much but then if it weren’t companies wouldn’t bother with aero wheels/trims in the first place.

 

[Rolfe]

Huh. Maybe they should think about the effects of the undertray warp, then.

ETA: Ah, I see it's not just about the aero trims, it's a full wheel swap for larger rims and wider tyres.

 

[JonnyG]

Yeah I watched that a while ago and was quite surprised at the difference too - around 18.4% more battery consumption with his heavier & wider 19" wheels & tyres vs standard aero trimmed 17"'s.

 

[Chequers]

Yeah I watched that a while ago and was quite surprised at the difference too - around 18.4% more battery consumption with his heavier & wider 19" wheels & tyres vs standard aero trimmed 17"'s.

What's that black thing sticking out in front of the Orange cars wheel ?

 

[siteguru]

I don't think that's real - I think that's just a photo edit thing in the wrong place.

 

[gredie]

As I saw this in one of his videos - The black thing in front of the orange car is a plastic add-on he installed just for the look. I think he ordered this at aliexpress.

 

[siteguru]

If that is real then it simply looks like a small air-brake, so it is bound to have an impact on drag and thus efficiency.

 

[Alexa]

Do you mean this part?

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Oh no, I know what you mean, I've never seen that before...

 

[siteguru]

As I saw this in one of his videos - The black thing in front of the orange car is a plastic add-on he installed just for the look. I think he ordered this at aliexpress.

Just realised that I think you're talking about the fins on the front air scoops. We're talking about this:

 

[Rolfe]

I don't see any sign of that on the actual video.

 

[MSvirus]

@magoulas fabrications Could probably answer for himself

 

[Torryhun]

Maybe had a go-pro attached to it for filming,

 

[wattmatters]

Just realised that I think you're talking about the fins on the front air scoops. We're talking about this:

Still hard to see, I outlined it to make it obvious:

If real, that would cause a substantial increase in aerodynamic drag. But it looks like something pasted onto the image.

 

[gredie]

Ah, now it see what the chat is about. I even didn't see that before.

 

[Rolfe]

It's only on the screen-grab. I can't see it on the video.

 

[acl]

I wonder how you swap out the wheels and get accurate readings when full rotation is now PI*19 inches of travel instead of PI*17 inches of travel. Unless there is a setting in some hidden engineering screen then all the speed, distance traveled and efficiencies are going to be completely out of whack. Think you're doing 70mph? If you have 19 inch wheels you're actually doing 78mph. And on top of that, larger tyres probably mean greater rolling resistance which impacts efficiency too.

 

[stevegus]

I wonder how you swap out the wheels and get accurate readings when full rotation is now PI*19 inches of travel instead of PI*17 inches of travel. Unless there is a setting in some hidden engineering screen then all the speed, distance traveled and efficiencies are going to be completely out of whack. Think you're doing 70mph? If you have 19 inch wheels you're actually doing 78mph. And on top of that, larger tyres probably mean greater rolling resistance which impacts efficiency too.

19 to 17 inches does not necessarily mean the entire diameter increases by 2 inches.

Often on a larger wheel there is a lower profile tyre that keeps the overall diameter relatively the same.

You need to know the tyre profiles

 

[Chequers]

I don't see any sign of that on the actual video.

You only see that side of the car in the video for a few seconds till the view cuts away.

 

[Rolfe]

Not there in those few seconds, though. Presumably that's the clip the freeze frame was taken from.

 

[wattmatters]

That camera mounted on the wing mirror would add 1-2% drag. Not enough to account for the reported difference but it would have helped to replicate it on the other car, or mount it inside.