Is the BMW Z4 M40i faster on track than its Toyota Supra cousin?

So yeah, we were hesitant to test this luxo-cousin to the sporty Supra on track, fearing there was nothing to be learned from seeing the more sedate take on a familiar hardware package get stomped.

Boy, are we glad we changed our minds.

On track, the Z4 is a delight, equaling the most recent Supra we sampled–also with the manual six-speed box–on the clock, on the data charts and in the seat of our pants. Actually, we’d be hard pressed to say the Z4 didn’t offer the preferred track experience in most areas, as it felt more composed than the Toyota.

Timewise, the Z4 clocked its best lap a scant 0.3 second slower than the Supra’s best–1:18.35 versus 1:18.63–although those tests were performed nearly two years apart from each other. Don’t sweat the three-tenths of a tick too hard. It’s just as fair to call it a tie.

1. The Supra (blue trace) and the Z4 (red trace) had identical acceleration in third gear. On this lap, which was our best for the Z4, we shifted to fourth gear and as a result probably lost some momentum to the Supra, which stayed in third. On laps where we kept the Z4 in third, however, mistakes elsewhere and track conditions kept us from beating this best lap. 2. Interesting anomaly here, as the Supra outpaces the Z4 in acceleration where they ran head-to-head in other areas. Ambient weather differences? 3. Overall, we’re prepared to call this a dead heat, especially when we see the Z4 outpacing the Supra at the tricky entrance to Turn 8. These charts are way more alike than they are different.

During that most recent test of the Supra, we praised the handling but also felt the chassis seemed a little edgy, at least when it came to feel and feedback. Well, the Z4 delivers similar traits, but it also seems to blunt the edge and make the car feel less nervous on track. In both cases, the VBox data didn’t really pick up any twitchiness perceived from behind the wheel. Instead, it showed good, solid speed curves with little variation through corners.

In fact, it’s difficult to look at the data and say conclusively why the Supra was a few tenths faster than the Z4. The Supra has better speed through a couple of slow corners and is consistently faster at turn-in on the FIRM’s square right-hand Turn5, but that could easily be due to track condition anomalies and not material car differences.

The Z4 is also consistently faster through the early and late sections of the FIRM’s Turn 8, which has three distinct cornering phases. The early turn-in phase offers a pretty good judge of feel and feedback–more confidence usually means more corner-entry speed. The middle section reveals a car’s pure road-holding ability as the chassis sits in steady state for a couple of seconds. The final stage sees the road camber go away just before throttle application, making for a complex exit as the front traction is balanced with thrust from the rear tires.

The Z4 slightly outpaced the Supra in those more complex sections, which seemed slightly out of character with its difficulty keeping up in the slower, squarer corners where transitional ability was also important. That’s why we’re inclined to call the track session a functional draw. The differences weren’t coarse enough for us to draw real conclusions, and the time and condition gap of the track were probably bigger factors than anything.

Interestingly, the Z4 and Supra used different methods to achieve their fastest laps. The Supra’s best lap came by staying in third gear for much of the 1.55-mile FIRM circuit, while the Z4 delivered its fastest time when we shifted from third to fourth just before the fast right-hand kink of Turn 4.

The data shows that we lost acceleration thrust by going to fourth, but we got a better entry and mid-corner performance out of the Z4 in fourth than in third. The VBox data shows that the aggregate time through that section was nearly identical, and most of the advantage of the fastest lap came in a section where both cars were in the same gear. So yeah, not much to glean there except for the fact that the B58 engine is wonderfully flexible and smooth, is likely underrated at 382 horsepower, and can be a great asset on track whether you’re lugging it and using the prodigious torque and minimal turbo lag or letting it wind to 7000 rpm.

We also sampled various settings from the ride control, which can be mixed or matched with settings for shock stiffness, throttle response and exhaust note. Our best laps came in the Comfort or Sport modes, with Sport+ having too aggressive a throttle curve for smooth power delivery and too much shock compression stiffness to soak up the curbs that are integral to a fast lap at the FIRM.

Comfort and Sport offer nice compromises, with both delivering great road-holding while the softest shock setting takes just a bit more time in the transitions. The balance here could all change with proper track tires and a more aggressive alignment, but we still prefer the most relaxed throttle setting in all cases. The B58 is snappy, responsive and impossibly flexible. It simply doesn’t need help from an overly aggressive throttle opening.

Plush Performance

The Z4 features all the luxury items expected in a modern BMW, yet the car still ran nearly as fast as the latest Supra. Remove any statistical noise, and we’d call it a tie.

So, what’s our conclusion here? Well, look, most people who are choosing a car for track use are still going to opt for the Supra, and they’re not wrong. It’s three cheap Miatas less expensive with a fixed roof and less weight.

We didn’t notice a lot of aerodynamic differences in our testing–acceleration seemed mostly consistent between both cars to and beyond 100 mph–but our test track doesn’t have the long straights of a Road Atlanta or Road America. As the speed increases, we can see the Supra’s slipperier lines paying off.

And really, the whole point of the Z4 is not to serve as a track weapon like the Supra–which, by the way, still comes with a complimentary NASA membership and track day. But we’ve learned that, despite its more luxurious focus and slightly swankier appointments, the Z4 gives up little to nothing to its more hardcore cousin in the performance department.

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