The 3.7-liter engine in the SLT is slightly harsh and too slow, and the four-speed automatic transmission needs another gear; we floored the SLT once at 40 mph, and the tranny didn't kick down and the vehicle felt gutless. The suspension takes bumps with a jolt, especially at lower speeds and mostly at the front wheels. And when we turned off the stability control and drove it aggressively around a hairpin turn, the front end washed out as badly as anything we've felt in a long time, on its Goodyear Wrangler on/off-road performance tires. This was surprising, because the Nitro is a rear-wheel-drive platform.

The R/T costs about $2700 more, but it's worth it. It's better looking anyhow, with more of its trim in the same color as the body, although those 20-inch chrome wheels are a bit much (as a $1405 option on the SLT, too bad you can't get 17-inchers on the R/T and save the money). Chrysler's R/T models are considered higher performance, but in this case it's not hot-roddy high performance, it's more literal: simply a higher level of basic performance by the engine, transmission and suspension.

The 4.0-liter V6 is a new single overhead-cam engine. It's rated at 260 horsepower, 50 more than the engine in the SLT, and it provides 265 pound-feet of torque at 4200 rpm. That's a lot of horsepower and torque, and we can't say that the R/T really feels like it has that much; but we can say that it accelerates up to 90 mph without messing around.

The R/T engine is quieter than the 3.7-liter in the SLT, and it gets nearly the same mileage: 17 city and 21 highway in 2WD, with 89 octane recommended but 87 acceptable. We got 16.7 mpg driving the R/T very hard out in the country.

The five-speed automatic transmission makes a world of difference in smoothness over the four-speed. However in manual mode, it doesn't listen. It only responds to a shift by the driver (at least this driver) about half the time. Most of the shifts to which it doesn't respond are about saving gas. It refuses to short-shift, or upshift before redline under heavy throttle. Nor will it upshift when you back off the throttle. As a result, passing on two-lanes is unnecessarily un-smooth. The upshifts near redline (6000 rpm) are also a bit slow, not as sharp as one might expect from an R/T. And the shift mechanism is not ergonomic; that is, the shifts are made by moving the lever from side to side, not forward and back, which would be easier on the wrist.

The handling of the R/T is reasonably sure-footed, and considerably more precise than the SLT; Goodyear Eagle tires help a lot. But it's the ride that's radically better, in this 2WD model. Theoretically the R/T's tuned suspension should be firmer, and surely it is overall, but it's also a lot more comfortable.