Another day and a milestone we have all been long looking forward to has come: driving around the M25 twice on one charge! Now for those of you who aren’t acquainted with the “M25″ it is the main motorway ring road around the capital, measuring 115 miles (184km) in length. The Tesla has been around it once on a single charge – we set ourselves the challenge of doing it TWICE on one charge! Now, calculations and range estimations had shown it could be possible but you can never be sure until you have done it for real…

Yesterday we launched the car to the press outside Imperial College in London and announced that we were going to embark on this feat. So after getting some evening rest from a busy few days we set off at 2.30am from west London to drive out to the M25, go around twice and make it back without running out of juice – a total of 250 miles (400km)…

So off we set into the dark at a steady pace of 55mph. Once you have done a few crossings and roundabouts you start to realise how bizarre it must look: an open top sportscar out at the middle of the night driven by two guys with balaclavas on We needed them because it was extremely cold – the wind offers no respite lashing at your face at motorway speeds…

Apart from the cold I have to say the M25 is a pretty boring road – nothing like some of the roads we will be driving in the Americas so I could console myself with that fact. On we ploughed with the energy meter dropping steadily but not too fast to cause any concern. Occasionally we would try and get behind a lorry to try and reduce our drag but I have to say unless you wanted to sit right behind it (which you dont want do in a car a fraction of its size) its wake didn’t contribute much at all… We got to the halfway stage after making stops at Clackett Lane Services and South Mimms. The few people that were around at the service stations got out to inquire about our mission. We met a guy who also had a huge battery pack in his car – although not to power the car but to power his SUBWOOFER! Which is apparently the largest subwoofer in the UK…interesting eh…

Anyway, the half time energy score was only 42% used so that gave us the confidence to power on into the next lap and up the speeds slightly so that we could get back to bed. On the second lap we averaged nearly 60mph – it would have been higher had it not been for hitting the start of rush hour. On the second lap we were also able to turn off the headlights – giving us an estimated energy saving of nearly 1kWh.

Early in the morning we arrived back home in West London – a round trip of 264 miles on the car odometer and the energy meter still at 14% full. This is slightly longer than the map suggested, probably due to the fact that our west London base is more than the 10 miles estimated away from the M25! And having done this at motorway speeds without recharging the pack with a single electron! This is a FIRST for electric vehicles and another important milestone in the bag for the project. The fact that we had so much left in the “tank” afterwards didn’t really provide for a very tense and nervy finish as I had imagined it to be. Anyhow, we have definitely fulfilled the design brief in building an efficient highway cruiser for a long distance endurance trip!

Even though these last weeks have been really tough on our sleep cycles, this was another night definitely worth staying up for. The feeling of success afterwards was emphatic – not only did we not have to recharge but we also put another few hundred miles on the clock without any mechanical or electrical problems on the car. Bearing in mind this is a car we have designed and built in 8 months and are still doing our first 1000miles of driving!! See here for a very crude video of the trip.  The distances on it are actually less than we covered as mentioned earlier.  Happy viewing!

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