Need for Speed has never looked likely to win a game of the year award, but for a long time it's been a fairly dependable series. You could more or less bank on EA delivering a fun arcade racer that didn't take itself too seriously, and because of this it's won a huge number of fans. Need for Speed ProStreet threw a spanner into the works with its drastic change of style from open-world arcade racer to closed circuit sim, but we thought Undercover was going to set things right. Playing an undercover cop who has to infiltrate an illegal street racing gang sounds like the Need for Speed of old, but it seems EA let this one leave the work shop without passing its MOT.

Undercover is set in the fictional Tri-City Bay area, a virtual world that consists of over 80 miles of roads and highways. As a cop with a love for fast cars, you're asked to go undercover in an illegal street racing gang, with the goal of infiltrating the operation, stopping the sale of stolen vehicles and bringing down the leaders. With Hollywood actress Maggie Q playing your handler Chase Linh, who appears in a number of live action cut scenes throughout the story, and plenty of EA's expected flashy presentation, things sound like they've returned to the Need for Speed of old, but Undercover is plagued with problems.

The most jarring problem you'll face in Undercover is the terrible frame rate. Previous games in the series have had the odd patch of trouble here and there, but in Undercover the game rarely runs smooth and more often than not chugs along at an unacceptable level. It's detrimental to the gameplay too, with the choppy visuals making racing at high speeds far trickier than it was surely designed to be. At times the game almost stops for a fraction of a second, before continuing at a pace not too dissimilar to how we imagine a modern game would run on the original PlayStation. It seems as if engine optimisation simply hasn't been done.

It might seem unfair to slam the visuals before talking about the gameplay, but we've just never seen a big budget, high profile release like this ship with such glaring technical problems. To make matters worse the city is bathed in a fair amount of fog and parts of it will suddenly appear as if teleported in from the Enterprise's holodec. During one high speed pursuit we appeared to be heading towards the edge of the map and a large mass of water, only for what looked like a small town to suddenly pop into view. Visuals aren't everything, but here they cause problems and suggest the game wasn't close to being ready for retail.

The driving is often exhilarating, but the game engine can't keep up.

It's a real shame, because the core gameplay is a strong return to what the Need for Speed games prior to ProStreet provided. Cars corner as if you're a Hollywood stunt driver, the sense of speed is incredible (especially from the bumper cam), police drivers are aggressive and smart, and the game world has a style that is pleasing on the eye. The main story to take down the illegal operation runs throughout, but you'll need to take part in various races, cop chases and damage runs (racking up damages that amount to a certain cost) in order to prove you can be trusted. With an open world to explore and the ability to instantly hop to an event you've effectively got the best of both words. As soon as you've finished a race you'll be shown the closest event and you're able to access it with a simple press on the d-pad.

If you've grown tired of the endless driving from point to point in order to start an event, you'll appreciate the more streamlined approach EA has taken here. It could be seen as hand holding, but you're always pushed along, moving from event to event and through the story, with very little down time. As you complete events you earn rep which goes towards your overall wheelman rank, driver skill points and cash - and the occasional keys to a new car. Cash can be used to upgrade the performance of your current cars (ranked in tiers from four to one) or to modify their appearance - the car sculpting seen in previous Need for Speeds returns and upgrading can be as simple as buying a package or as complex as tuning various aspects of your ride.

Cops are aggressive, but they're not very good at arresting you.

Although set in a city where civilian drivers go about their business events often take place on closed off roads, or ask you to do laps of a set circuit. We're not against this from a game design point of view, as race events more or less rely on everyone taking a certain route (with the odd short cut thrown in). Cop evasion, outrun and city damage events don't limit your play area, giving you the whole map to drive in, which again is a good design choice. Evading cops can be great fun, with the AI drivers getting incredibly aggressive as they box you in, slam you into walls and try to spin your vehicle. Having said that, my first arrest came more than six hours into the game, so they're not the hardest to evade - the many signposted destructible objects help block paths, allowing you to drive to safety.

Sadly the Outrun events seem woefully designed and far too easy to exploit. You have to stay ahead of an opponent for a set amount of time (say 60 seconds), in a completely open city. Because there's no track, being ahead simply means not letting your opponent pass you on the same stretch of road. So, all you need to do is lose your pursuer and you're laughing. At points we were able to slow to a crawl and just watch the mini-map as our opponent struggled to find us, while the clock ticked away until we'd won the event (usually so convincingly that we were said to have Dominated, which earns you more rep points and bonuses). Conversely, if your opponent takes a sneaky corner and you drive on, you might as well restart straight away, as you're not making up the gap in time.

If there's something EA got right it's the new highway battles. Taking place entirely on massive stretches of highway (motorways for us Brits) you have to get a certain distance ahead of an opponent, weaving in and out of traffic while travelling at insane speed. The game defaults to the bumper cam here, making for some exhilarating driving. It's also the ideal mode to make use of whatever nitrous you've installed and your Speed Breaker (which effectively slows down time so you can move through narrow spaces). Doing so also earns you bonuses for heroic driving (something the game encourages), which the handling model effortlessly allows you to do.

There's still no shaking the feeling that Undercover needed more time in the shop.

Outside of the single-player campaign you've got a number of multiplayer modes for up to eight players. Our favourite is the Cops N' Robbers game type, which is pretty self explanatory, requiring one team to play as the robbers, picking up and dropping off money, while the cops try to prevent them from doing so. You'll also be able to take part in the traditional circuit races and sprint events, with solid online performance throughout. A fairly simple photo mode has been included, which allows you to upload pics to EA's Need for Speed website, and the Xbox 360 version supports fairly run of the mill Achievements - sadly there are no trophies in the PS3 game.

We had extremely high hopes for Need for Speed Undercover, not to be a ground breaking game, but something that was highly polished and a great deal of fun. After EA's recent run of quality, it came as quite a shock that Undercover simply doesn't feel ready. The in-game performance is frankly terrible and one of the main event types is deeply flawed. We can't deny that there's still fun to be had here, especially in the highway battles (and with some of the dialogue), but we simply can't recommend a game that performs so poorly that it's at times unplayable.