Overall Track Performance
For a car that isn’t aimed directly at track performance, the BMW 550i xDrive really stepped up and set a very impressive lap time.
It definitely wasn’t the easiest vehicle to tame on the track and I had my share of moments trying to extract the most from it. But the underlying strength of the car, the twin-turbo V8, kept shining through.
Overall Road Performance
The BMW M550i is an excellent car for people who want loads of power and torque without spending significantly more coin on the upcoming M5 Competition.
This is a large luxury sedan that’s comfortable and sure-footed on the road. It’s more than good enough to give you endless thrills off the track, where it probably feels more at home.
Our 0-100km/h testing showed a figure of 3.92 seconds, which is pretty close to the official claimed figure of 3.8 seconds.
Engine
There’s really not much to complain about here! It really feels like you have the full 390kW of power and 750Nm of torque at your disposal from the 4.4-litre twin turbo V8 at any time.
At no point did I think, I really could do with more power! It was more a game of, how can I use this power in the best way possible to achieve a good lap time?
The engine’s response is excellent and the drivability was smooth and predictable. You have a nice blend of power and torque, which overlap well and create smooth, seamless power delivery.
I don’t want to be too unkind to the chassis, but this engine really carries the car around the track.
Braking
The brakes are okay, but not exactly what you want on a track. They lack the initial bite at high speed to inspire confidence and after a few heavy stops, there’s a drop off in performance.
I think this is to be expected of a car of this size and with such strong acceleration. Feedback wasn’t great either, and I struggled to really be late and committed in the braking areas.
Chassis
It’s a reasonably nimble chassis for the size of the car and I could actually be quite aggressive with my driving, especially on the shorter corners and with quick changes of direction. The problem is when the car is heavily loaded either in a long corner or during heavy braking and entry, it doesn’t have the support to deal with it.
It feels like a lot of weight is on the front corner and it ends up falling over and understeering. Remember, this is at the absolute limit and when driving at 80 or 90 per cent it performs just fine.
I did have a couple of moments where I over committed on fast corner entry and the car went from understeer to oversteer, which was entertaining at 150km/h.
I was impressed at how well it handled riding the inside curb on the slow corners without getting upset. This is the first car that could really attack turn three at Queensland Raceway’s Sprint circuit, which helped set it up for the exit of turn four. I just had to give away a little on entry to achieve this.
Transmission and Differentials
I was happy with the gear change and the speed of the shift helped with the lap time, because it accelerated so smoothly. I would say that on the track it would be ideal if it had longer ratios in the lower gears. You have so much torque and usable power, corner exit would be smoother if I could hold a longer gear.
That being said, I don’t think it really affected the lap time and I was always in the right gear.
To be honest, I wasn’t 100 per cent sure about the differentials. Don’t take this as a negative, it was just hard in a few laps to gain a full understanding what was occurring. Initially, traction was excellent and they seemed to be working very well, but as the tyres dropped away, I noticed a bit more slip and the car became more difficult to drive.
They feel like they are very free, which is great when you have good grip. When the grip dropped away, the car became more inconsistent.
I also noticed when I put the loaded wheel on the outside ripple strip, that there was a small loss of grip. This could have been either the damper or the differential not dealing with the vibration and the change in grip. As I mentioned, I need a little more time with the xDrive system to understand it completely.
Suspension
As you would expect in a luxury sedan, it’s very under-damped for aggressive track use. On the first few laps I overdrove the car and the corners carried on too long. This is a big mistake when you have such a strong engine up front, as it takes far too long to be able to get to full throttle.
Traction was very good, but the movement on braking and corner entry was quite significant, I really had to guide the car to the apex without any sharp inputs. If the load was only for a short amount of time, such as change of direction, the damper had support, but if the load continued then the car would roll further and lose grip.
The problem was there was not enough force back against the road, which is what you are after on a track.
Steering
Steering was good, but I felt like it lacked a little bit of feel near the limit of grip. This is a combination of the whole package from the tyres, through the suspension and steering. I didn’t have the last subtle detail of when I was at the edge.
Wheels and Tyres
The Bridgestone Potenza tyres offer a pretty balanced compromise for road and track, they lost a little performance over the test, but actually recovered well for the second outing.
I did struggle to find the limit of grip, between the suspension, steering, and tyres, which made the lap time a bit inconsistent.
Driver Aids (Electronics)
I turned the traction and stability control off for all the laps, which I would not recommend for everyone. I had a couple of moments where I over stepped the mark and had to catch it. Seeing it isn’t a track car, I didn’t see the point in trying the ESC as I feel like it would have intervened too much.
Cockpit (Ergonomics)
I was well-positioned in the car, and able to get the seat low enough and at a good angle so that I wasn’t moving around too much. No problems here at all.
Lap Time
Well here is the surprise… 57.23sec! The BMW M550i jumps straight to near the top of the CarExpert leaderboard.
It definitely took a bit of effort and thought to get that time, on my first outing I pushed a bit too hard and tried to carry too much corner speed. I still cracked into the 57s, but only just.
After a bit of reflection and really focusing on corner exit to make the most of the engine, we knocked another half a second off. For a car that isn’t track focused, this is a great lap time and I can’t wait to see what the M5 can do. But next we will bring you its bigger brother, the BMW M8.
Atko’s 3:
- Be very smooth on high speed corner entry
- Position the car in the middle of the corner so you can be aggressive on the throttle
- Don’t be afraid to attack changes in direction, it responds well here.
