Having the wrong smell in a car can cause speeding, dozing and road rage, according to the RAC Foundation.

Having the right smell can “help a driver to recognise dangers earlier, stay focused on the road ahead, forgive other peoples’ driving errors and even find a bit of romance”.

Conrad King, the RAC Foundation’s consultant psychologist, said: "More than any other sense, the sense of smell circumnavigates the logical part of the brain and acts on the limbic and emotional systems.

This is why the smell of perfume can turn men into gibbering idiots, the smell of baking bread can destroy the best intentions of a dieter and the smell of baby powder can make a child averse individual become quite broody.

"When we bring cars into the equation, however, the ability of various smells to over or under stimulate us as drivers can have catastrophic results."

Dangerous smells to be aware of are:

camomile, jasmine, and lavender – these are all used to treat insomnia and can cause drivers to become over relaxed behind the wheel. They are also present in many "flowery" air fresheners

the smell of fast food wrappers, fresh bread or pastry - these can cause driver irritability, a preponderance to speed and an increased chance of involvement in road rage because they can all make drivers feel hungry and in a hurry to satiate their appetites

the smell of fresh cut grass, pine woods or roadside flowers - while relaxing some drivers, this can put others into a nostalgic frame of mind where they daydream of swooping down country lanes and fail to appreciate the speed at which they are travelling. For hay fever sufferers there may be the added problem of streaming eyes and sneezing.

a combination of leather seats and oil – this can make some older drivers remember the thrill and sense of freedom that came with their first cars. They could potentially then unconsciously adopt the risk taking behaviour of much younger drivers.

certain perfumes and aftershaves – these can have a strong sexual association which may make both male and female drivers more interested in carnal matters than motoring matters. Whole memories, complete with all associated emotions, can be prompted by smell.

Smells beneficial to driving include:

peppermint and cinnamon - improves concentration levels as well as making drivers less irritable.

lemon and coffee – these smells are good for clear thinking and high concentration levels.

new car smell (a combination of cleaning products and organic solvents etc) - tends to make people concentrate better and also take more care with their driving.

sea air – a blast of salty sea air can encourage deep breathing which relaxes the muscles, relieves stress and calms the mind.

For those people who think that a neutral smell in their car would be best, studies of astronauts found that a lack of odour was often profoundly disturbing, leading to irritability and even olfactory hallucinations.

A pleasant smelling car can also enhance the driver’s appeal to a partner. In earlier RAC Foundation research, when asked to name the things about a potential partner’s car that might add to his attractiveness, the car’s scent came out as one of the top answers.