First, I enjoyed reading your post - some well though out points that you obviously put some time into. However, your numbers are way off, not sure where you're getting them, but the real numbers are below.
Originally Posted by Shraka
The SLK 350 has 32.9% more power than the new MX5, and 38.39% more torque. That means it will be about 38% faster down low, and 32% faster up high. A whole third more power and torque is quite a lot though, it's just not the twice as much as it seems on when quoting figures in a void. Torque is all well and good but you need to know how much weight that torque is trying to move. A vehicle with 3000nm and 2000kw that is 10 tonnes is going to be the same speed as a vehicle that has 300nm, 200kw and is 1 tonne.
High torque can feel a lot faster than low Torque, despite being the same speed. I know a lot of 5.0ltr Commodore owners who feel their cars are much faster than my 1.8ltr Honda Integra, and are unhappy when they find out that in fact my Integra can keep up, and in many cases go faster.
Just to show the difference, here are the two cars 0-100km/h times (0-60mph):
Mx 5: 7.10 s
SLK 350: 5.60 s
So the Mercedes is actually quite a bit faster.
Actually, your numbers are seriously off.MX5 SpecsSLK350 Specs
Here are the real figures:
SLK350 curb weight: 3318 lbs
SLK350 horsepower: 305hp
SLK350 torque: 265 ft-lbs
SLK350 EPA est: 19/26mpg
SLK350 0-60 time: 5.3 secs
(SLK350 0-60 time and horsepower ratings pulled from the model review by edmunds, which is more accurate than their spec page, and which match the info listed in my MB manual: 2009 SLK First Drive
SLK350 horses-per-pound: 0.0919 hp
SLK350 torque-per-pound: 0.0798 ft-lb
MX-5 curb weight: 2602 lbs
MX-5 horsepower: 158hp
MX-5 torque: 140 ft-lbs
MX-5 EPA est: 20/27mpg
MX-5 0-60 time: 7.5 secs
(MX-5 0-60 time pulled from the edmunds model review: MX5 Model Review
MX-5 horses-per-pound: 0.0607 hp
MX-5 torque-per-pound: 0.0538 ft-lb
As you can see here, in reality, the SLK350 is much more powerful than the Miata, to the point that they can't even be considered in the same class of vehicle. And this would make sense, since you will never see them racing in the same bracket in track racing, autocross, etc. The 2.2sec difference on the 0-60 times alone speaks pretty well for itself.
And trust me, get into an SLK350, take her for a spin and you will see that there is seriously no comparison between these two cars, performance-wise. To top it off, the fuel mileage is literally about 1mpg different between the two cars. I've since added Green Air Filters to my SLK, which increase my mileage about 2mpg in mixed driving on average, so I'm now getting better fuel mileage than a stock Miata.
It's not fair to compare the two cars, though. It's like comparing the Cayman S to the Mazdaspeed 3. They're not in the same class at all, and doing so unfairly makes the MS3 look like a crappy car. Same with the SLK350 vs Miata.
My only point earlier was that anyone who would say the SLK is "Miata-ish" or "girly" is seriously ignorant, to the point of absurdity. When I hear such things, I start hearing the Deliverance theme song in the back of my head, and I just giggle. Whatever, let the rednecks be rednecks, that's my motto.
Originally Posted by Shraka
You're right, the SLK is in a different class. It's a more powerful GT car, and less of a low power handles-like-it's-on-rails racer. I actually quite like them and would consider taking one over an MX5 so I by no means think you made a bad choice, it just seemed you were implying that the MX5 was crap compared to the SLK 350, which it isn't. Ultimately if you enjoy driving it that's the main thing.
A stock SLK350 is built with luxury in mind, and lacks the "handles-like-its-on-rails" characteristics of the AMG sports package, which I have added. This includes much stiffer sports suspension, lowers the car by about 1 inch, adds larger tires and brakes, etc. While I can't speak for a stock SLK350, because I don't own one, I can definitely say for sure that my car with the sports package handles like it's on rails. It's not a Lotus, for sure, but I'd say the handling is just slightly softer than that of the Cayman S, with similar turning characteristics, which impressed the hell out of me when driving it. There are very few cars on the road with similar abilities. I've also added the Kleeman headers and x-pipe setup, so I'm probably seeing about 10-20 more hp than a stock SLK350.
Definitely not saying the Miata is crap, however. I really enjoyed the ride when I test-drove it, and was surprised at how peppy it felt. The handling in that car was pretty excellent, which is to be expected. However, the MX5 feels "quick" where the SLK350 feels "FAST." You can't do burnouts in a Miata, nor do you often have to worry about the rear getting happy when downshifting to 5th at 80mph. Also, the cabin in the MX5 is quite loud with the top up or down. If price is a concern, the Miata is a great car. It's worth noting that you can pick up 2 slightly-used (as in, one year old) Miatas for the price of a single SLK350. I just felt that for overall thrills, the SLK fit my needs better and I was willing to pay the additional costs. Again though, I think the Miata is a great car and personally think people who put it down are just ignorant. And when I hear people call them "girly" or "gay" cars, I just think those people are either douchebags or just closeted homos (either way, they suffer serious insecurity issues and obviously doubt their own manhood).