A decade or so ago, car stereos were a commodity item. You could specify your vehicle with a decent one, but fitting something better aftermarket could improve features considerably, particularly when CD players replaced tape. But now many cars use highly integrated hi-fi systems, which might incorporate the feed from the trip computer or even a built-in satellite navigation system. Upgrading something like this with a standard single- or double-DIN unit could lose you some important functions. So how do you add the latest audio features, such as DAB radio and iPod connectivity? Look no further than Pure’s Highway 300Di, which can add a host of useful functions to your existing hi-fi.

The Highway 300Di is not a single- or double-DIN unit. The package comes in three parts. The control unit is designed to sit at a convenient place on your dashboard. It fits into a cradle, and can be removed and stowed away if you’re worried someone will break into your car and try to steal it, thinking it’s a sat-nav. The main circuitry, however, is hidden inside another unit which is meant to be permanently installed somewhere invisible, usually behind your glove compartment.

The Highway 300Di can connect to your existing stereo in a variety of ways. The simplest is via an auxiliary line in, if your current hi-fi has one. You don’t lose this in the process, though, as this is simply passed through. The other alternative is via FM radio, with two different options. One involves transmitting a local FM radio signal, which you then tune into on your main stereo. The other involves connecting the Highway 300Di directly to your FM radio aerial, called FM direct injection. This might prevent you using the radio to pick up other FM channels, but in most cases simply ensures a clean signal for the Highway 300Di that is devoid of interference. With the FM radio method, you can choose the frequency the Highway 300Di transmits on, to avoid existing channels in your area.

The third part of the package is the most unusual. Acknowledging that DAB radio, like digital TV, can be fraught with dire reception, Pure has chosen to turn your entire car into an aerial. The antenna connection from the main circuitry unit is fed up to your windscreen, and then passed through to a unit which is stuck onto it at the top corner. This then attaches to the car roof magnetically. The aerial unit sits in a frame, and can be removed relatively easily with a special tool, as automatic car washes may damage it. If your car has an aluminium body, this obviously won’t work, so there’s an alternative film antenna.

Obviously, this is a pretty complicated arrangement of different parts, and only the very adept would be advised to install it themselves. Fortunately, Halfords will also fit the device for free, so long as you bring your car to the store for the procedure, which takes about half an hour. Mobile fitting is extra. The end result is a unit that’s integrated seamlessly into your existing stereo. We tested the Highway 300Di hooked into the auxiliary line- in of a ten-year-old head unit, with the circuitry inside the glove compartment. The only evidence of its existence was the two leads – one for the line-in pass through, the other a USB connection.

Controlling the Highway 300Di is pretty simple, and will be familiar if you own one of Pure’s other DAB radio products. Most functions are operated with a knob on the front, which cycles through options, with a push to select the current one. There are some playback controls ranged around this and a couple more buttons on the top. Your first task is to choose one of the four input options. Aside from the auxiliary pass through we already mentioned, the USB connection supplies two more choices. You can plug in a USB memory key, stocked with MP3 audio and playlists, and play its contents. All the usual tagging is supported, and shuffle mode is available.

Similar functionality can be had for iPods, iPhones and iPads. You will need to supply the appropriate USB cable yourself, but support for i-devices is essentially universal. Your device will be charged whether the Highway 300Di is in iPod mode or not, but when it is all your track, album and playlist information will be loaded and you can control playback with the Highway’s dial. We found that it was even possible to control videos, although obviously only the audio comes through the Highway 300Di to your hi-fi. So you could, in theory, rig up an iPad for your passengers to watch movies.

The DAB radio is the main draw, however. Simply twist the main knob to cycle through available stations, and press in to select. We found reception to be excellent, with lots of stations being picked up in the areas we tested around London and the Home Counties. You can also quite easily store presets using the favourite button on the top. Press once to call up the listing, find an empty slot, then press and hold down to store the current station. Up to 30 presets can be stored, and recalling one merely entails scrolling through the listing and pressing the knob to select.

The Highway 300Di has some other tricks up its sleeve, too. The playback controls work with DAB radio as well. You can pause playback, and the unit will buffer up to 15 minutes of audio, depending on the station bitrate – great if you’re listening to drama or your favourite track, and need to mute the audio for some reason. You can then rewind and fast forward. If you’ve been listening to a station long enough, you can rewind even without pausing, too.

These functions will even work for up to 15 minutes without the key in the ignition. So if you stop for petrol, you can lock up your car to pay, then get back to right where you left off. Similar to this is picnic mode. The unit will work for an hour without the keys, so you can leave the main stereo on, leave the Highway 300Di on, open the doors, and enjoy music outside the vehicle. But you can also take the keys away to avoid pesky thieves. One thing we found the Highway 300Di didn’t like, however, was removing the control unit without turning it off first, and replacing with the car already started. This made the control unit unresponsive, although leaving the vehicle off for an hour or so returned it to normal.

Verdict

The Pure Highway 300Di is a specific solution for a specific problem. If you have an easily replaced single-DIN head unit, alternatives in this format with similar functionality including DAB radio can be purchased for the same or less, and will be considerably easier to fit. But if your car has a system you don’t want to swap out, for a variety of reasons, the Highway 300Di does its job extremely well, and can bring your car’s audio capabilities bang up to date.