Exposing BMW\’s Efficiency Concept

We know for a variety of reasons that this concept has nothing to do with the 1001 front wheel drive model BMW is developing as some outlets are reporting. We know that this car is not electric powered only (it has a tailpipe). What we now see in better detail is the front lights, which are looking a lot like the Vision Efficient Dynamics.

Wealso know is that this is NOT a performance car because of the width of the tires since the tires are narrow, something we all need to take turns at high speeds and get the power down to the tarmac are wide tires; or do we?

One of the easiest ways to cut drag on a car is to decrease the width of its tires, so from an efficiency standpoint that is something that must be done if you are trying to design the most efficient car possible. The one caveat is, that by decreasing the width of the contact patch it decreases the overall lateral traction alloted to the vehicle.

When you design a car like this you think outside the box, way outside the box and try things that are non conventional to give you the upper hand. BMW could have used variable suspension geometry to help curb handling issues with this car but that is costly and rather difficult to implement, they went another route to making sure they could offer efficiency and performance.

BMW and a well established tire manufacturer have been rumored to be working on developing a narrower, low rolling resistance tire with a variable radius as part of the Efficient Dynamics push and this is the first we are seeing of it. The outside radius of the tire being greater than the inside.

This new tire is being designed to improve the shape of the contact patch, less so the size of it.As the outside wall collapses down on contact with the ground it will widen the contact patch and (through some very interesting engineering) somehow maintain enough stability so as to offer razor sharp handling (anything less would be a failure on this project).

Thanks to Robert for the semantics and engineering lesson, clarifying things nicely.

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  • Robert1

    Well, you certainly went off on a “tangent”.. excuse the pun. That was poorly written to say the least.

    Before you attempt to write about technical topics, you should probably have some background or education in engineering or mechanics. If you did, you would understand that even without these new concept tires being designed, you are not losing ANY contact patch area by making a tire’s section width narrower (all other variables the same, all other tire dimensions the same, constant temp and pressure, vehicle weight, etc..), contrary to what is written in your article.

    With ANY current tire, as you go to a narrower section width you are changing only the shape of the contact patch. This has handling implications because the shape of the contact patch will play its role in determining vectors of grip. Lateral grip is decreased as the contact patch narrows.

    This new tire is being designed to improve the SHAPE of the contact patch, less so the size of it. As the outside wall collapses down on contact with the ground it will widen the contact patch and (through some very interesting engineering) somehow maintain enough stability so as to offer razor sharp handling (anything less would be a failure on this project).

    Hope that helps you fill in the gaps.

    • I always think of contact patch in terms of width, smaller was the wrong word to use- narrower is much better.

      I understand the concept but poorly explained it, your method was much better and appreciated. Thanks!

  • JonPD

    Maybe just me, I had no issues understanding what you wrote Michael. The principals are not exactly requiring an engineering degree to comprehend.

    An interesting approach to the fine line between efficiency and performance.

  • Aruv

    Right on Robert. I saw the same stupid thing said on another BMW forum or site. I’m pretty sure the VED concept can reach amazing speeds even on 190 tires. Sure, more work needs to be done to the body frame and structure to balance it out, but nonetheless it won’t affect perfomance.

    Michael, poorly explained or not, that’s what came across. And you said the same thing in another article.

    • Considering I just received the information and I am certain that I am the only one with the info-I know it has it has never been written anywhere about the tires. That being said some people seem to know everything. I am sure someone else will claim it as their info by the end of the day. Funny how some people just troll here and complain that posts are not up to their high standards.


  • lava

    I think that we need to revise our use of “performance”. I consider a car that is highly efficient to be a high performance car – if its pushing the standards of efficiency in the industry then its high performance.

    We’ve wed performance to sporting or speed and handling. That was perhaps fine when speed and handling were the only boundary that anybody tried to push. I think we need to be more specific in our discussion these days as its clear efficiency is a new area of performance where a car can excel.

  • Khalid

    No offense Michael, but this time BF was late to the game with these news. The tires width and other info were reported first by others. Can’t win it all, and that’s fine.

    I think what they meant was that the information wasn’t accurate from an engineering point of view, and as you said in other comments, that’s not your background, right?

    No one was trolling, but on an open forum, anyone can say whatever they want to, same as you post …whatever you want to.

    And did you just update the article? cause if you did, it would be nice to say update and give credit to Robert1.

  • Khalid

    I’ll take that back, credit was given to Robert, but to someone new, this looks like an entirely new post and they will be confused by all the comments left here.

    Still…stop being so defensive, this is part of a dialog.

    • Not being defensive, but show me where the specifics of the tires are elsewhere on the net- and I am not talking about them being narrow which is quite obvious and anyone can see. I am talking about the fact they are a new concept that is being tested with a different inside and outside diameter which was the point of that part of the post.

      I am all for dialog and I thanked Robert for constructive criticism with merit. Anyone can read his comment as well.

      Enough said.

  • Khalid

    These are the same tires as on the VED car. Nothing new.

    Moving on, you’re still defensive with your Enough Said comment.

  • Que

    So let me get this straight, is BMW designing a tire or one of the major tire, and if so, do we know who yet? I happen to be an Mechanical Engineer, and I thought the write up was a bit vague, but not bad. That said, I personally like diagrams to clarify the write up, as language is sometimes difficult to convey the idea, hence we have drawings, diagrams, and good old math.

    But with that said, a small contact path can work, if the weight and good old CG is brought down. The tire, be it important one, is just a part of the equation that makes a good car handle well.

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