Tråd: Sejlads Ved

Biler, der coast kunne overhale hybrider i kapløbet om ultimative economyA par uger siden, jeg afprøvet Mercedes E300 Hybrid det meste af vejen fra Brighton til London i RAC Fremtidige Car Challenge. Ved den tid, jeg nåede Exhibition Road i det centrale London, trip computer, der sagde, at jeg var i gennemsnit 65. 7mpg. Der er lige på biler brochure lover af 109 g/km. Problemer er, køreteknik for at udtrække den slags brændstof økonomi grænsede til det ekstreme.
Ruten op fra Crawley nødvendige brændstof-besparelse deltagere til at skalere en stejl smule af den Nord-og Nedture, samt en del af hurtigt strømmende M25 og en lang strækning af travle byveje fra Putney Hill til Kensington.
Alle disse dele af ruten arbejdet mod de forskellige elektriske og hybride køretøjer, fordi klatring, hurtigere og hurtigere, og rangering sammen i tung trafik er den mest energi-ineffektive. Ja, ved den tid, jeg havde ryddet North Downs turen computer var der angiver blot 48mpg.
Id havde mulighed for at øve med E300 for et par dage på min normale pendling køre og opdagede, at den bedste måde at køre op på den økonomi, der var lige til kyst, ned ad bakke, hvor det er muligt. Den E300 har evnen til at slukke sin motor, og gå ind i, hvad Tyskerne kalder sejlads tilstand. Hvorvidt dette er sandt sejlads tilstand (hvor transmissionen går også ind i neutral, forlader bilen til at rulle frit) jeg kunne ikke finde ud af, men det er utroligt effektiv.
Da jeg rullede ind på M25, det var klart nok for mig til at komme væk med en 60 mph cruise og så viste det sig ind i en lang, mild, ned ad bakke. Så dramatisk er den energi, der spares ved friløb, der, efter mindre end 15 minutter på M25, jeg afsluttede med en 55mpg gennemsnit på skiven.
Den A3s 50 mph hastighedsgrænsen var ideel for minimal brændstofforbrug og jeg yderligere snydt af slipstreaming en solo Vauxhall Ampera. Ved den tid, jeg forladt for Putney, computeren læs 67mpg, og jeg var overrasket over at falde lige et par mpg af den tid, jeg har kastet seks urban km fra Kensington. Men for alle Mercedes kompleks Hybrid drivetrain, i form af besparelser på brændstof, intet cames tæt på at løbe ved enhver lejlighed.
I sommer kørte jeg en prototype Audi A6 med intelligent sejlads. Der anvendes en 3D-sat-nav system (så det, vidste, at når downhill-strækninger af vejen blev nærmer sig) og kombineret det med indlejrede oplysninger om egne træk og rullemodstand. Dette gjorde det A6 til at beregne, hvornår det kunne slukke motoren, og kun langs kysten på kinetisk energi. Drevet forsigtigt, det var overraskende, hvor ofte A6 motor ville falde tavs.
Min oplevelse af prototype A6 og produktion Mercedes har gjort mig mere og mere sikker på, at fremtiden ligger ikke i komplekse benzin-elektrisk drivetrains, men nedprioriteret normale motorer (eventuelt, ligesom A6, kombineret med en lille, elektrisk drevne, turboladere), koblet til en ægte sejler-tilstand transmission.
Selvfølgelig, for den entusiastiske driver, peger dette i retning af en dyster fremtid. Biler med nok selvstændighed og intelligens til at afgøre, hvornår de skal dræbe motoren og kyst, i jagten på den ultimative økonomi, tyder på, at driveren vil kun være med på turen.
Men mens enkelhed og billigt af aktiv sejlads overbeviser mig er det en no-brainer, godt at håbe på, at bilproducenter omfatter en off-kontakten.

Cars that coast could overtake hybrids in the race for ultimate economyA couple of weeks ago, I piloted the Mercedes E300 Hybrid most of the way from Brighton to London in the RAC Future Car Challenge. By the time I reached Exhibition Road in central London, the trip computer said that I had averaged 65. 7mpg. Which is right on the cars brochure promise of 109g/km. Trouble is, the driving technique needed to extract that kind of fuel economy verged on the extreme.
The route up from Crawley required the fuel-saving entrants to scale a steep bit of the North Downs and as well a section of the fast-flowing M25 and a long stretch of busy urban roads from Putney Hill to Kensington.
All these parts of the route worked against the various electric and hybrid vehicles because climbing, accelerating and shunting along in heavy traffic are the most energy inefficient. Indeed, by the time I had cleared the North Downs the trip computer was indicating just 48mpg.
Id had the opportunity to practise with the E300 for a few days on my normal commuting run and discovered that the best way of driving up the economy was just to coast downhill wherever possible. The E300 has the ability to shut off its engine and go into what the Germans call sailing mode. Whether this is true sailing mode (where the transmission also goes into neutral, leaving the car to roll freely) I couldnt find out, but it is amazingly effective.
When I rolled onto the M25, it was clear enough for me to get away with a 60mph cruise and then it turned into a long, gentle, downhill. So dramatic is the energy saved by coasting that, after less than 15 mins on the M25, I exited with a 55mpg average on the dial.
The A3s 50mph speed limit was ideal for minimal fuel use and I further cheated by slipstreaming a solo Vauxhall Ampera. By the time I exited for Putney, the computer read 67mpg and I was surprised to drop just a couple of mpg by the time I shunted six urban miles to Kensington. But for all Mercedes complex Hybrid drivetrain, in terms of fuel saving, nothing cames close to coasting at every opportunity.
In the summer I drove a prototype Audi A6 with intelligent sailing. It used a 3D sat-nav system (so it knew when downhill stretches of road were approaching) and combined it with embedded information about its own drag and rolling resistance. This allowed the A6 to calculate when it could shut off its engine and just coast along on kinetic energy. Driven gently, it was surprising just how often the A6's engine would fall silent.
My experience of the prototype A6 and the production Mercedes has made me increasingly sure that the future lies not in complex petrol-electric drivetrains, but downsized normal engines (possibly, like the A6, combined with tiny, electrically-driven, turbochargers), coupled to a true sailing mode transmission.
Of course, for the enthusiastic driver, this points to a bleak future. Cars with enough autonomy and intelligence to decide when to kill the engine and coast, in the pursuit of ultimate economy, suggests the driver will only be along for the ride.
But while the sheer simplicity and cheapness of active sailing convinces me it's a no-brainer, well have to hope that carmakers include an off-switch.