I don't think the "L" means low.It means lock up.Effectively if you start off in "L" the gearbox stays in first gear without changing up automatically.If you start off in "D" allow the gearbox to change up to second and then shift to "L" you will only have first and second available until you shift back to "D"Its very handy for towing a caravan because when in "L" you have engine braking which you don't have in "D"