09-17-2014, 04:25 PM | #1 |
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Track review
Hi,
Got the opportunity to drive the M4 on the track today. The car is my wifes car and she did 5x 20m sessions in the car. I did 1x session driving and 1x as a passenger instructing. For comparison, I also did 1 session in a Jaguar F type R (provided by Jaguar), which is similar size to M4 but much more powerful (404kw and 640nm). Also I did multiple sessions in my own dedicated circuit racing car, Mini R56. My overall impressions are that this is a very competent car, but ultimately it is a grand tourer, and it is not a racecar. It is a little big, heavy and ponderous (as is the E92). The power delivery had me stumped the first couple of laps. It seemed so laggy, with the power only really coming on at 5000rpm when it would really pull hard. Then I realised I had left the traction control on! You cannot drive this car on the track with the traction control fully on! When I looked the light was flashing continuously on the straights, and it was pulling power. This is not just from low speeds. I was hitting 230km on the straight, and the light was flashing continously up to around 170kmh! I then put the car in mdm mode, and presto! The power delivery and acceleration was in a different world. With traction control on it felt slower in a straight line than an E92, with it off it is much, much quicker! Our car has the steel brakes. They worked fine with no fade. However, the feel and modulation was not great, and the pedal feel was quite heavy. This was on stock pads, and I'm sure a more track focussed pad would be good. Suspension was really impressive, but couldn't feel a huge difference between sports or sports plus. Lateral grip was good, and the car felt nicely controllable. Turn in and mid corner balance were excellent for a car of this size. Plenty of feedback, but ultimately you feel the size of the car. Ran on the stock tires, which were surprisingly good, and wore relatively well. However, I am sure they had something to do with the traction issues in a straight line. I was amazed at the fuel economy. We used much less fuel than I was expecting, and much less than in other similar cars I have tracked. Overall the car performed well. For a street car / grand tourer with limited track use I think it is ideal. That is what my wife bought hers for, and it is ideal for that. If you want to race / club race, and set lap records etc then I think you have the wrong car. It will be fast, and with work eg tyres, brakes etc will be even faster. However, I think it it is a car where you can go 80% fast extremely easily, and neither you or the car will break out in a sweat. It is a "hero" type car for HPDE's which are not timed. You will seem fast and do this easily. However, if you are competitive and timing, to extract the last 20% of the performance envelope in this car will be hard IMHO. By comparison, the Jaguar was interesting. I have driven a few Jags on the track over the last 18 months and this was by far the most impressive. Despite the extra power of the jag I felt it was pretty much line ball with the M4 in a straight line. Suspension and brakes were similar too. Happy to comment on any particular points if required. Robbo |
09-17-2014, 04:58 PM | #2 |
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What octane fuel?
Any issues with heat soak? What were your peak oil temps? Did you drive DSC completely off, or only MDM? If you drove DSC fully off, how was the transition from understeer to oversteer with mid-turn throttle? To what extent can you smoothly steer it with the throttle? What tire pressures did you run hot/cold? How was your tire wear (at each corner and across each tire)? Thanks! |
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09-18-2014, 12:05 AM | #3 | |
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I did not data log the air intake temperatures, but the car did 20m sessions in ambient 25c with no obvious problems, and certainly did not lose power during the session. Oil temps barely moved from where they normally sit in street driving. I did turn DSC fully off. The rear grips very well, and it during my short sessions I did not experience any lurid oversteer. The tail gets a little twitchy on corner exit with full power down, but the diff seems to work well. I would need more time to give a better analysis I aimed for 35psi hot. Started the first session at 30 cold, and had to bleed a little out, 1-2 pounds as the day went on to keep it in range. The tire wear was good. The surface, especially on the rears grained up a little, but not bad. There was much less rollover and sidewall wear on the front than I was expecting, certainly less than on the e46 or e92 with stock tyres. I suspect the stock suspension geometry and alignment is pretty well set up and more track friendly than e46/92 stock and the tyre is actually not too bad. |
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09-18-2014, 04:16 PM | #4 |
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Appreciate the review. I had a lot of the same impressions when it took my M4 out for its first track sessions. I'm probably a little more optimistic on the F8x being a little better track car ultimately than you are. Obviously it's not a racecar, but I wouldnt call it a grand tourer just yet (it'll need better seats for that ) either. It falls somewhere in between.
Did you time your laps in the M4? I kind of thought I was really slow with the M4 compared to my E36, but wasn't as far off on time as I thought I would be. I'm going track both for awhile and see if I can get the M4 close.
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Road course laptimes for BMW M4 2015 6MT
WHP East Track: 1:04.880, Arizona Motorsports Park: 1:54.352 Road course laptimes for Porsche 911 991.1 GTS 7MT WHP East Track: 1:02.770, Arizona Motorsports Park: 1:48.889 |
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09-18-2014, 06:24 PM | #5 | |
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Can you elaborate further on the remaining 20%? In your opinion, what makes that 20% for this car to be difficult to attain, what factors may be difficult or risky to get to that level, and would some adjustments or modifications may help? Thank you again. |
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09-18-2014, 07:16 PM | #6 |
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good write up.
when you say it feels big, do you mean it feels piggy like the e90 was, or even more? @FTS i thought you instruct at hpdes? means that 20% doesn't apply to you |
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09-18-2014, 07:44 PM | #7 | |
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Frankly Robbo's review is red meat for me. I am so looking forward to figuring out that 20% with this car that I can hardly wait, love those challenges. Data logger is ready, track wheels/tires are being worked on, looking for camber solutions and possibly A/R bars |
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09-18-2014, 08:15 PM | #8 | |
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Seat of the pants the M4 feels like it has more spring the the e92 comp had. Does anyone know the M4 spring rates? |
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09-19-2014, 05:12 AM | #9 | |
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I don't want to give the impression that the car was slow though, the times were very respectable compared to my times on the same day in my dedicated circuit racing car. |
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09-19-2014, 05:23 AM | #10 | |
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A good analogy on what I mean that most of us would understand is a comparison between street tires and racing tires (eg type r or full slicks). Street tires lose grip progressively, squeal, and generally let the driver know what is going on. When they do let go it is predictable. Racing tires are quicker, and have more grip. However, the loss of grip and how they behave can take some getting used to, and they can unnerve some drivers. Going from E92 to F82 is like making that progression in tires. The F82 is quicker, has more lateral grip and is a more race focussed product. You can definitely go faster. However, learning where the limit is and how the car will behave on the edge of the limit, how it puts the power down and how the throttle modulation works etc will take some seat time and confidence in the car. Hope that makes sense |
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09-19-2014, 08:30 AM | #11 | |
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Just pulling your leg I am eager to try out my M4 at the track in 2 weeks. What I am looking for is a good dual purpose car. One that can serve me well on the DD and road trips while still delivering good and fun performance at the track. So far my experience with all my previous M3s has been just that. For sure, the F8X are not time attack weapons out of the box; very few cars are straight off the showroom floor. Last edited by CanAutM3; 09-19-2014 at 08:42 AM.. |
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09-19-2014, 08:56 AM | #12 | |
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look forward to YOUR track review also Thanks OP for the good review. Very good news about power not dropping off and temps being stable
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