Ever since they were launched, something has been holding these two cars back. In the Cayman's case, it's Porsche. That its engine is in its middle theoretically means it could be a better-handling, technically superior car to the company's own 911. And on Porsche's watch, that ain't going to happen. Porsche tacitly admits that the Cayman has never been allowed to be all it could be, lest it puts the squeeze on its rear-engined, range-topping (and, coincidentally, surely more profitable) sibling.

The Lotus Evora has had its own, arguably more serious issues. The Evora, which is scheduled to make its North American debut at the New York auto show on April 21, is a car which its maker put everything into, but wasn't sufficiently complete. It's a car for those who love their handling, but also one for those who are prepared to overlook issues relating to drivetrains and interiors. And, one suspects, there aren't quite enough of those people around.

The two cars here – suffixed by an R and an S, respectively, might change some of that. I say "some" because, in the Porsche's case, you can't help thinking, it'll never be "all." Think of the $66,000 Cayman R as a Cayman S plus, rather than a Cayman GT3. Power is up by just 11hp to 326hp, still appropriately less than a base 911 Carrera 2. The real tweaks lie elsewhere.

The R has shed 119lbs over the regular Cayman S – and you can feel that some of it has come via the removal of noise insulation. It sounds like a door has been left ajar. There's more wind, road and engine roar than I remember from my last outing in a Cayman S. Maybe some of that's down to the aluminum doors. Some of the rest of the weight is down to the removal of the air conditioning and the stereo. There are the lightest wheels currently fitted to a Porsche, too (shared with the Boxster Spyder). Mostly though, I reckon, it's the removal of heavy-duty foam.

The $75,000 Lotus is no lighter than the regular Evora. But the S's power hike is rather more substantial than the Cayman R's, thanks to the attachment of a supercharger to its 3.5-liter Toyota-sourced V6. Some 345hp (that's more than a 911 Carrera) means it has had a 70hp power increase and, unlike the Cayman, that is the significant part.

Lotus couldn't resist tweaking the chassis; there should be a touch more grip, but more importantly less roll at the rear and an increase in stability around the straight ahead. But ride and handling were never the problem with the Evora. We knew it could handle more poke. Now it has it.

From the start, the Evora also needed a finer interior for the price. Today? Well, it still does. There's now little wrong with the way it's built, but as we drive it into the country – a not unreasonably lengthy journey – you still can't help but notice a few areas that could be improved. Readouts are poorly resolved and hard to read in sunlight. Switches are obscured by the steering wheel. The pedals are offset. And if the Porsche sounds like you've left a door ajar, so too does the Lotus. Its extruded aluminum chassis tub feels like it has been lined with carpets. And even though the seats are leather lined and should be more comfortable than the carbon fiber-backed Porsche items, the reality is that the Cayman has the superior driving position.

The Porsche cabin, for all its mainstream-finish materials that could furnish the inside of any German hatchback, feels the more civilized, more mature environment. Not sure I'd specify some of the body-color trim, though, and I'd keep the optional air-con and stereo; even if you're a track-day enthusiast, on a long summer drive I reckon you'd not get far before regretting leaving them out. It doesn't sound like much, though, does it: 119lbs on what's now a 2,855-lb Cayman? A tank of gas, a very small passenger. But still, if you've driven Caymans S and R back to back, you can feel it combining with the 10 extra nags, or maybe an improved engine response. Definitely, there's a touch of extra urgency to the way it goes. It's a rapid car, too; 0-62mph takes a claimed 5.0sec, and Porsche's claims are usually conservative.

To top it off, the Cayman's engine is a peach. The 3.4-liter flat six sounds sharp, hollow and smooth. Standard on the R is Porsche's short shift for the 6-speed manual, which gives the box a short throw. Very short, actually – and coupled with a touch of notchiness on the way through, it's not the most satisfying of gearshifts, although it's positive and accurate enough, and you'd find it hard to mis-shift.