It shouldn't come as a surprise that iPhone is already well-stocked for decent driving games. After all, racing is one of the easiest and most logical ways to show off the iPhone's accelerometer feature.

So, we've had three impressive iPhone racing games already, in the shape of Crash Bandicoot Nitro Kart 3D, Cro-Mag Rally and GTS World Racing.

Now Gameloft has entered the fray with Asphalt 4: Elite Racing, a souped-up version of the mobile game of the same name, and part of a franchise that's already extended to N-Gage, DS and PSP.

The idea remains the same: 3D street racing in cities around the world, with you earning cash and unlocking new cities and cars as you progress. The cities are varied - from staples like LA, Paris and New York to quirkier choices including Dubai, Saint Petersburg and Mumbai.

Meanwhile, the cars are fully licensed, allowing you to get behind the wheel of real models from the likes of BMW, Aston Martin, Lotus and Ferrari, not to mention bikes from Kawasaki and Ducati. The way these cities and cars are unlocked as you pass earnings milestones gives the game long-term value.

There's a choice of events too, from straight races through to Cop Chase, where you have to make your way through your rivals to catch the one at the front, and Beat 'am All, where you have to destroy as many rivals as possible.

Oh, there's a tuning option too, where you unlock parts for your car to improve its performance. It's not exactly obvious, mind - you access the tuning feature via a distinctly unobtrusive spanner icon at the top of the Car menu screen.

That's the structure, but how does the game play? Very well, thankfully. There are three ways to control your car: two based on touch and one based on tilt.

Of the former, one involves tapping the right side of the screen to turn right and the left to turn left, while tapping on specific buttons to nitro boost and brake.

The second involves actually turning an on-screen steering wheel. Meanwhile, the tilt method is what you'd expect - tilt your iPhone left and right to steer, while tapping on the boost and brake buttons when required.

Weirdly, you can only switch between these methods by tapping an iPhone button at the top of the screen while actually racing - it's not made obvious from the start, which has led to some confusion in initial user reviews on the App Store.

Of the three methods, the steering wheel one is pretty useless, the wholly-touch method provides the most control, but the tilting one is undeniably the most fun. What's more, Gameloft has done a good job of tuning the accelerometer mode to make your cars easy to control.

Asphalt 4: Elite Racing looks good for iPhone, with polished 3D visuals and varied cities to race in. Pop-up doesn't seem to be an issue either, but there's a hitch: this appears to have come at the expense of speed.

The game isn't super-sluggish, but it can get a bit jerky at times. And while the speed is okay, this is one of those driving games that makes you wish the developers had compromised a tad more on graphics in favour of sheer pace.

Of course, this being an iPhone game, by the time you read this review, Asphalt 4: Elite Racing may have got one or more updates upping its frame-rate.

Otherwise, this iPhone version follows its mobile parent in terms of the gameplay, with nitros playing a key role. Just racing won't get you far - it's all about collecting and/or earning nitro boosts and using them to zoom past your rivals, ideally while smacking them up in the air in Burnout-style 'takedowns'.

It provides a welcome element of strategy to the gameplay. And that's the big selling point to Asphalt 4: Elite Racing - it's got the most depth of any iPhone racing game, thanks to all the cars, tracks and tuning parts you can unlock (oh yes, and 'ladies' - a feature we'll gloss over here).

It's a much more ambitious game than GTS World Racing, its closest rival on iPhone. Yet they get the same mark - how come? It's all to do with expectation.

Having promised so much with its wealth of vehicles, tracks and racing modes, not to mention its excellent graphics, Asphalt then narrowly fails to deliver on the other crucial feature: speed.

It's a strong 8/10, mind, but if it was a little more pacey, it'd be a stone-cold 9/10. As it stands, it's the best iPhone street-racer (as opposed to Crash Bandicoot Nitro Kart 3D, which is a kart-racer).

But for once, this is an iPhone game for which we're eagerly awaiting some performance-related updates.

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