One's a slippery minx of a two-seater. The other has a 1,050-pound maximum payload, seats five and looks like it was carved by Eskimos. Your first reaction is that the 2008 Audi R8 and the 2007 Jeep Grand Cherokee SRT8 have nothing in common.
Think again. What other American nameplate offers the Audi R8's fundamental layout of all-wheel drive paired with a V8? That's right — the Jeep SRT8 stands alone. It's also one of the swiftest SUVs ever made. Don't laugh. This truck can give the Audi a run for its money.
So they're more alike than they appear at first blush. Then again, conventional wisdom says to always go with your gut instinct.
Its rear-biased all-wheel-drive system and centralized powertrain mass disguise just how rapid the Audi R8 is when it's hammered at full speed from corner to corner. Its cold numbers represent serious performance — 0.98g in ultimate grip on the skid pad and 73.8 mph through the slalom — yet what's really impressive is the first-rate poise of the R8's chassis. This is one of those rare vehicles with enough straight-line traction and cornering grip to match its high-performance engine, so the Audi's 420-horsepower 4.2-liter V8 actually feels less powerful than it is.
A 4,722-pound SUV with the same feel of immovable mass as Stonehenge shouldn't hope to challenge the dynamic prowess of the midengine Audi. Yet the Jeep SRT8 cleaves turns with surprising precision. Stiff suspension underpinnings deliver a firm, confident ride with minimal body roll, resulting in a more than respectable 0.84g result on the skid pad and 61.9-mph speed through the slalom. In driving maneuvers at 7/10ths effort, the Jeep effectively emulates a well-sorted sedan.
Braking proves no contest. The R8's shortest stop from 60 mph is a remarkable 103 feet, beating the Jeep's best by 25 feet. And while the Jeep brakes faded after the first stop, the Audi just kept getting better and better with successive stops. The Audi braked within half a foot of its best stop even after 12 rapid-fire stops.
Audi wins the dynamics element of our comparison handily, which should come as a surprise to no one.
Drivability, Audi Category
The Audi R8 is a dignified sports car, mercifully free of those elements that make other supercars impossibly taxing in real-world use. It doesn't have goofy scissor doors, and you won't rip the crotch of your jeans while clambering across a wide door sill because the R8 doesn't have one. Nor is its cabin cramped — two lanky 6-foot-2 dudes will fit comfortably with room to spare. The Audi R8 even rides astonishingly well, thanks to its two-mode magnetorheological adaptive dampers.
The Audi's low-stress nature is evident in the carefully polished action of every control interface. The lever directing the six-speed manual gearbox clack-clacks through its metal gate with a well-oiled lack of effort, and the clutch engages so progressively that the car practically drives away from a stoplight by itself. The steering is light and direct, though serious drivers will find it shy on feedback.
At cruising speeds, road noise in the R8 is subdued, and only a muted burble from the V8 located just inches aft of your ears reaches the cabin. Throttle response sharper than a Ginsu knife makes drivers of all skill levels seem like pros while downshifting, as revs can be matched with precision.
And thanks to the careful airflow management expressed by its bodywork, the R8 feels unflappable at the ohmygod velocities it is capable of quickly attaining.
The R8 is, in a word, effortless.
Drivability, Jeep Category
As a sport-utility, the Jeep offers something the Audi never can — an SUV's tall driving position. This provides a great view over the top of the R8 and pretty much anything else on the road shorter than a Chevy Kodiak. Inside the Jeep's cabin you'll find a functionally sound but uninspired environment that occupies the opposite end of the style spectrum from the Audi.
But the R8 can't serve as an indoor hockey rink like the SRT8 can. At 69.0 cubic feet, the Jeep offers nearly 10 times the maximum cargo capacity of the Audi.
Those hoping to tow a Zamboni with an SRT8 have another thing coming, however, as the SRT8's tailpipes are located right smack where the trailer hitch would go. Nor is the SRT8 intended for even moderate off-road use, though in circumstances where inches matter, it will take you places that would leave the R8's flat underbelly scraped and bleeding.
Jeep wins on practicality, and the Audi truly raises the bar on sports car user-friendliness. In that respect, it's a tie.
On the Dyno
With 420 hp at its command, the output of Jeep's 6.1-liter pushrod V8 matches that of the direct-injection 4.2-liter DOHC V8 in the R8. To help reveal the different personalities of these engines, we ran both car and SUV on a DTS all-wheel-drive chassis dyno.
First, the Audi spun the rollers to the tune of 339 hp, demonstrating a nicely flat torque curve that peaked at 277 pound-feet. Then the Jeep belted out 373 hp and 360 lb-ft. Pick a point anywhere in the Jeep V8's rev range and you'll find it generates more torque than the Audi, but this pushrod V8 hits the wall at 6,300 rpm whereas the Audi pulls all the way to 7,900 rpm. This higher-revving nature lets the Audi take better advantage of gearing.
What stands out most is the difference in peak power. Both V8s are connected to similar all-wheel-drive systems, so driveline losses should be roughly similar. And since both engines are claimed to generate the same power at the flywheel, they should put down very close to the same power as measured at the wheels. Yet the Jeep threw down a full 34-hp more than the Audi, so what's going on here?
One conclusion might be that either the Jeep's output is underrated by the factory or the Audi is overrated, or some combination of the two. Another theory is that the high-compression Audi V8 is more sensitive to fuel octane than the relatively understressed Jeep engine, and the crummy 91-octane fuel here in California affected the Audi's output more than the Jeep's.
The R8's dash to 60 mph in 4.2 seconds and its run through the quarter-mile in 12.7 seconds at 110.7 mph demonstrates that license-incinerating performance and a calm disposition can coexist peacefully.
However, the Jeep's five-speed automatic transmission means that victories during stoplight showdowns can be exacted over inattentive R8 drivers. Looking at our data, we can see that the Jeep launches harder than the Audi up to about 20 mph. Just brake-torque the big V8 against the five-speed slushbox, and when uncaged the Jeep drops the remaining truck pretense and heaves forward as if it had been snatched by a passing F-16.
There's no wheel-spinning drama, only the bellow of the big-cube pushrod V8 as it smashes the SRT8 toward the horizon. Four Goodyear run-flat tires endow the Jeep with plenty of traction, and 60 mph falls in just 4.7 seconds followed by a quarter-mile sprint in 13.4 seconds at 102.3 mph.
Even though the Jeep is easier to drive fast around town, the R8 still makes the numbers that count.
Index of Performance
Although the R8 is ultimately quicker than the SRT8 in every facet of our instrumented testing, the SRT8's performance is more accessible both in everyday use and by virtue of its $45,465 price as tested. This is a colossal $78,280 less than the $123,745 R8 we tested.
In short, the Jeep flat-out clobbers the Audi in Index of Performance.
The R8 manages to be striking, although it doesn't exude the heartstring-tugging beauty of a car like the Alfa Romeo 8C. Instead, the Audi's shape blends modernity with arty details while delivering full-frontal road presence.
If you imagine the R8 as a warmly lit sculpture at L.A.'s Getty Center museum, the Jeep is like slapping open an issue of Juggs under a bank of fluorescent lights. Chrome dubs and bespoke center-mounted tailpipes extensions differentiate it from lesser Grand Cherokees, but any dressed-up SUV has all the sensuality of Donald Rumsfeld at a security conference.
In our time with these vehicles, the R8 averaged 13.0 mpg and the Jeep 12.8 mpg. The EPA says the Audi should net 13 mpg city/20 mpg highway and the Jeep 11 mpg city/14 mpg highway (per EPA's 2008 standards). It seems the Audi has the edge in fuel conservation.
But this perspective neglects the Vegas Factor. Road trips to Sin City in the R8 are limited to one companion. If you have four friends (unlike us), then three of them will have to find their own ride to Vegas.
Using two cars consumes more fuel than if everyone packed into a single SRT8. The Jeep's backseat is not ideal for long trips but, hey, we're going to Vegas, baby. On the way home no one will be awake enough to care, unless someone has fallen in love with Misty and stayed behind.
Thus, in a Greenpeace-befuddling leap of logic, we judge this aspect of vehicular performance to be a tie.
Listen to Your Gut
With the 2008 Audi R8, the people at Audi have succeeded in combining performance and sophistication in equal measure. Despite its low-slung look of mobile astrophysics, the midengine R8 is a real car in the vein of Porsche's 911, something that you wouldn't think twice about hopping into and driving across the country.
In comparison, the 2007 Jeep Grand Cherokee SRT8 is one-dimensional and antisocial. Some might even say it's a vulgar novelty. It might trade much of its off-road and towing capability for murderous straight-line acceleration, but the surprise factor is why we love it. The only other SUV that's more fun in activities that have nothing to do with SUVs would be "Grave Digger," the monster truck.
In the end, the Audi R8 amassed more points in our comparison than the Jeep, despite its enormous price penalty. But you already knew that. Your gut instinct was right again, wasn't it?
The manufacturers provided Edmunds these vehicles for the purposes of evaluation.