1.9 Z3 vs NA/NB Miata

Everyone knows that Miata Is Always The Answer. But have you considered a 1.9 Z3?

M44B19

Even though the iconic BMW E30 M3 was a 4 banger, when people think of BMWs, they usually think of inline 6s. Aside from the E30 M3, there isn’t much love for the 4 cylinder models. I had the opportunity to race an E36 318is at one point and team orders were to keep it under 5.5k rpm. As the power didn’t really come on until high revs, this made for a pretty tame ride. However, I did have a lot of fun in it, and I was amazed at how little fuel it used. I think it was in the same neighborhood as the Yaris at 4 gallons per hour. Since that time, I’ve been looking at various BMWs with the M42/M44 engine. In the US, these include the E30 318is, E36 318is, 318ti, and Z3. I briefly owned a 318ti, and I thought it ticked off a lot of boxes for me (RWD, hatchback, light, good MPG). The one box it didn’t tick was roadster. I’ve always loved the experience of driving a convertible, especially on track. I find the Z3 to be nearly perfect for me.

But what about the 6 cylinder Z3s (and Z4s) you ask? I don’t see the need for more power. I only want to drive so fast on track unless I have a complete roll cage around me. And I see absolutely no reason to sacrifice fuel economy for power on the street. I never drive fast on public roads. The small thrill isn’t worth the huge risk. I can’t imagine how horrible it would be to hit someone. Another reason to favor the M44B19 is that the inline-sixes tend to tear out their differential mounts. The 2.3 might be okay, but I would worry about the 2.5, 2.8, and 3.0 engines.

Z3 vs. Miata

Pretty much every review of the 1.9 Z3 talks about how underpowered the car is. And it’s largely true. The power to weight is very similar to a 1.6 Miata. But does everyone complain about how underpowered Miatas are? Only a little. Instead they are praised for their great handling. I’ve owned a couple Miatas and I’ve driven 4 different Miatas on track. All were excellent. But I’m here to tell you that the Z3 is just as excellent. In fact, I like it even better. The Z3 interior is much more refined and the whole car feels more solid. Well, it ought to, it’s a lot heavier. Let’s compare them.

• NA6 2092 lbs, 115 hp, 110 tq
• NB 2348 lbs, 140 hp, 119 tq
• NC 2535 lbs, 158 bp, 139 tq
• Z3 2600 lbs, 138 hp, 133 tq

On my first track day, I was able to put down a 1:34.0 on $85 Federal Evoluzion ST1 tires at Thunderhill West. That’s definitely in NA Miata territory. But honestly, I’d rather have the performance of an NB. The Z3 makes about the same power as an NB, but it’s ~10% heavier. So how about a 10% more powerful Z3? There are engine builders that sell 200 hp M42B19 engines, but I’m in California and have to stay street legal. What are my options? Bolts-ons? ECU tuning?

Flash Tune

Midnight Tuning Solutions is a Canadian shop that specializes in tuning BMW engines. The BMW M44B19 isn’t just a simple chip swap. You have to ship your DME to them and have it flashed. However, for about $300, they promise +18 hp and +12 tq, and 7k redline. Imagine a Z3 with 156 hp,145 tq, and a 7k redline…

Fuck imagination, take my money. I haven’t been to a dyno, so I don’t know the specifics, but it feels like a different car, especially at 4k and above. And about that rev range, I’m not sure it has a rev limiter anymore. I had it well above 7k and it didn’t cut. That’s something to be careful about. Overall, I’m really pleased with the improvement. 13% more power is really noticeable when you don’t start out with much, and $300 isn’t that much for something that is invisible and still passes smog.

Power:Weight

I weighed the Z3 today and it was 2640 lbs with a full tank. How do I weigh cars? I have a bathroom scale that reads up to 700 lbs. I shim all the wheels up to the same height as the scale and then move the scale from wheel to wheel.

• Z3
  • 2640 (car) + 170 (driver) + 10 (gear) = 2820 lbs
  • 156 hp * 0.83 = 129.5 wheel hp
  • 21.78 lbs/hp
• NB
  • 2350 (car) + 170 (driver) + 10 (gear) = 2530 lbs
  • 140 * 0.83 = 116.2 wheel hp
  • 21.77 lbs/hp

At least on paper, my lightly modified Z3 is nearly identical to a stock NB Miata. And the torque numbers are more than 10% in its favor (145 to 119, +22%).

Conclusion

Miata is always, always, a great answer. But they are getting harder to find and the prices are going up and up. For the same money, you can now pick up a 1.9 Z3 that was probably owned by someone who didn’t abuse it. If you like slow roadsters, like me, consider the 1.9 Z3 with an ECU flash.