Cadillac XLR - New Supercar
By John
Hartley
Clearly influenced by the styling the Mercedes-Benz SLK, the new Cadillac XLR shares
the squared off look of other recent Cadillacs. It doesn’t look bad at all, although
the headlamps look as if they have been squeezed to fit alongside the wide grille. The
performance puts it up in the supercar class.
Top speed is limited to 155 mph, and it can get to 60 mph in about 5.7 seconds – that's
slightly quicker than the Jaguar XK, thanks to the larger engine. Other competitors include
the Mercedes-Benz SL and Porsche 911.
Looks can be deceiving. The car is wide and low, and looks big. In fact, it is quite
compact, just 177.5 inches long and 72.2 inches wide. The car looks pretty good, particularly
from the side. And you get a very practical SLK-lookalike opening roof. I guess most
convertibles will be ‘metal’ convertibles soon, and the rag tops will disappear – maybe
not on all supercars. To save weight, the roof of the XLR is aluminum and magnesium.
Good power output
Also, the XLR has quite a lot of power: 326 bhp at 6,500 rpm and 312 lb ft (423 Nm)at
4,400 rpm from GM’s Northstar 4.6 liter V-8, which could work a bit harder – 350-360
bhp, which would not be difficult to get from this engine, would make things more interesting.
As it is, it is enough to give the car quite a shove, and as the Northstar has an aluminum
block and head with dohc and four valves per cylinder, it revs well. Variable valve timing
improves the spread of power, too.
The engine is coupled to a rear mounted five-speed automatic transmission – 5 speeds
put it at a disadvantage against the European supercars which mostly have six-speed automatics,
but it is designed to give sporty shifts. Because the box is rear-mounted and the engine
is fairly well back, front/rear weight distribution is 50/50.
New frame concept
Based on GM’s new platform for sporty cars shared with the Corvette, the XLR has a fairly
light frame of hydro-formed steel tubes. Hydroforming changes the shape quite dramatically,
putting in bends, changing the section to a rectangle and so on, making a lightweight
frame. The passenger compartment is aluminum, and the body panels are composite plastics.
This is a structure that can compete with many a supercar.
This is a fairly light structure, and despite the high level of equipment, the car weighs
a healthy 3,643 lb (1,654 kg) which is just 130 lb more than the new lightweight Jaguar
XK, and of course quite a bit more than the Corvette which has a lower spec but bigger
engine.
Double wishbone suspension
Suspension is the familiar Corvette design of double wishbones front and rear with transverse
leaf springs. The result is a simple, lightweight system that gives more roll stiffness
- resistance to roll - than coil springs. Also, the spring rate is progressive, so it
irons out big bumps in the road almost as easily as little ones. There is also a front
anti-roll bar.
To save weight, the double wishbones front and rear are aluminum; of course, the composite
leaf springs are light, too. Leaf springs of this type - just one leaf - are actually
quite advanced technology as they don't locate the wheels, and involve some clever manufacturing
techniques.
The dampers are the new continuously variable electro-magnetic type, and the steering
is speed sensitive, so you get more assistance at low speed.
As this is a Cadillac, it comes with a high specification. For Europe, navigation, and
heated/cooled seats are standard as are adaptive speed control and a head-up display.
The interior, with its wood, leather and aluminum trim is quite pleasant
On the road
Built in the same plant and to the same concept as the Corvette, the Cadillac XLR is
best thought of a softened up Corvette intended for those who want a better ride.
Visibility is good thanks to slim pillars in the opening roof, and the almost flat hood.
Like the Corvette both the instruments and driving position are good. There is also a
head-up display which shows only the speed and which gear you're in, and you don't seem
able to switch off. Pity. I did not find it useful.
The steering is not bad at all, and the XLR turns in well, as you'd expect with that
weight distribution, but once you start pressing, you start to feel a little understeer
coming in, which is not a bad thing for the market this is aimed at – more the luxury
sports car that the hard charging supercar driver. But the car does not corner as fast
as you could with more neutral steering.
The automatic is good. In D, the performance is not bad at all, and the kick-down is
quite aggressive. There's also a manual mode. Push the lever across to the left, and
then nudge it forward for up, and back for down. This works extremely well, and actually
is a manual. I mean, some of these actually shift up when you hit peak revs. Not this
one; it just lets you stay there till you're ready.
Overall, the Cadillac XLR is a good addition to the ranks of sporty two-seater luxury
cars, but not up to the standard of the Jaguar XK nor the Aston Martin V8 Vantage. Others
to consider include the more powerful and sportier Corvette and Viper SRT-10. Too new
to rate is the Audi R8
Super Cars
John Hartley is editor of http://www.fast-autos.com,
an online magazine devoted to fast cars and supercars, where you can read the latest
articles about fast cars. He has written from many of the world's top auto magazines,
and has written many books about cars and the auto industry, including 'Suspension and
Steering Q&A' and 'The Electronics Revolution in the Motor Industry'.
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