On the second day of my week-long stint as an Uber and GrabCar driver, I committed a traffic offence - holding up a bus on a full-day bus lane.

A passenger had booked an Uber ride from Bugis Junction at 5.40pm but he called as I was reaching the mall to say that he was waiting in Victoria Street "at the traffic light (junction) below the ERP gantry".

His pick-up spot was not just at a corner of a busy four-lane junction, where a speeding Ferrari killed a taxi driver and Japanese passenger in 2012, but also the start of a red bus lane - where cars are forbidden from 7.30am to 8pm on weekdays.

He and two other passengers took their time to climb in, oblivious to the fact that there was a bus waiting behind.

"You should not have asked to be picked up here. The fine is $130," I said. "It is a dotted red line," he retorted. The dots mean cars can filter into and out of the bus lane.

We remained silent throughout the rest of the 10-minute ride to Ritz Carlton Hotel.

Later that evening, my Uber rating fell from the five stars I scored on my first day of driving to 4.5 stars. The passenger must have given me a poor mark for arguing with him.

By the time my week-long stint was up, I had come across at least 10 more inconsiderate passengers, who wield over drivers the disproportionate power of dishing out poor ratings.

TWO HOURS FOR A 'LICENCE'

I rented a 7½-year-old, grey 1.6-litre Toyota Corolla for $50 a day. I also paid $65 to start a limo car rental company, a requirement set by Uber and GrabCar to meet Land Transport Authority (LTA) rules.

I was accepted by both firms as a driver within two hours of visiting their offices. The sign-up took about an hour and the training, 30 minutes. In contrast, it took me more than two weeks of training and taking and passing an LTA test to obtain a cab licence in 2013.

At Uber, I did not even have to fill in any form.

At GrabCar, I struggled to complete a four-page form asking for details such as my traffic offences stretching back seven years, and even the serial number of the Android smartphone I was using to install the company's app.

Uber has a 600-word code of conduct spelling out broad principles which apply to both drivers and passengers, including asking both to treat each other with respect and obey the law.

GrabCar's was painfully detailed and I had to agree to pay damages if I breached the code.

Some of the rules were straightforward, such as "do not set your own fares", "do not solicit passengers to make personal or extra booking arrangements" and "do not recommend other taxi booking apps to your passengers".

But one stumped me - "you are prohibited from having or keeping weapons of any kind... in your vehicle or on your person for any reason". I had to put away my trusty Swiss Army knife.

Uber and GrabCar run 30-minute training sessions for new drivers as many as six times each weekday at their Midview City offices in Sin Ming Lane.

"Do not discuss politics with the passengers," said the GrabCar trainer, adding: "And do not contact passengers after the trip. We have complaints of drivers disturbing (the) pretty passengers."

Only GrabCar inspected the condition of my car. "Do not put too many personal things in the boot," said a staff member after a cursory check of the car's interior and the boot. It took less than a minute.

And I was all set to go.

INAUGURAL FARE

My first passenger was a man who used Uber to book my car at 7.38am, for a trip from his Serangoon Gardens corner terrace house to his Anson Road office at Springleaf Tower.

He was polite and patient when I made wrong turns getting out of the sprawling estate and to his office.

"Good luck for the rest of the day," he said as he got off .

His fare for the 15.7km, 29-minute journey was $18.63 excluding the $5 in Electronic Road Pricing (ERP) charges. My actual earning was $14.90 after Uber deducted a 20 per cent commission of $3.73.

If I were driving a regular taxi, the trip would have cost about $22 in fares, excluding ERP charges. And I would have earned $21.70 - which was $6.80 (46 per cent) more. The taxi company's cut would have been 30 cents for the call booking.

As the week progressed, I found that GrabCar and Uber fares during peak hours - if there is no surge - are cheaper than for cabs. This is good news for passengers but that means less for drivers.

The rest of my first morning took me to River Valley, Hong Kong Street, the International Business Park in Jurong East, the Science Park in Buona Vista and Changi Road. By 10.30am, the Uber app showed that demand had dried up so I took a break.

I was back on the road at 4.30pm, plying the city area. I picked up passengers at PWC Building in Cross Street, Grand Copthorne Waterfront hotel in Havelock Road, Eu Tong Sen Street, Kampong Eunos, LaSalle College of the Arts and High Street, and ferried them to Great World City, Chinatown, the Substation in Armenian Street, Clarke Quay and Suntec City.

By 9pm, I had made 12 trips involving 14 passengers.

Nine were booked by foreigners, including several from India, an Australian, a Spaniard and a Panamanian student studying at the Nanyang Technological University.

I followed the same routine for the rest of the week, using both Uber and GrabCar's apps to look for passengers during the morning and evening peak hours.

The Uber app was easier to use. It is linked to Google Maps and all payments were by credit card, which meant that I did not have to do the maths or keep small change.

But unlike GrabCar, Uber does not let drivers know where the passengers are heading when jobs are assigned to them.

An arts student that I picked up at LaSalle during the peak hours said her destination was Clarke Quay - a 2.5km ride that should have taken less than 10 minutes - but she wanted to drop off her art work at her Jervois Road condominium and pick up her mother along the way. The detour meant an 8km trip, taking just over half an hour.

Drivers should be told exactly where their passengers are heading before they commit to giving a ride.

UBER v GRABCAR v CABS

By the end of the week, I had made 64 trips for 88 passengers and a poodle called Hugo.

There were distinct differences between those who used Uber and GrabCar. The former was favoured by foreigners, while my GrabCar passengers were almost exclusively locals.

Foreigners booked 25 of the 44 trips - about 60 per cent - I made using Uber. But of the 20 trips I made on GrabCar, only one was made by a non-local - a Chinese Canadian and his female Singaporean friend from a Sims Avenue condominium to Raffles Hotel.

The passengers gave various reasons for picking Uber and GrabCar over regular taxis.

Lower fares were a big draw.

"There are no booking fees or peak hour surcharge," said a Singaporean accountant who booked an Uber trip from her Cross Street office to her River Valley condominium after work. She paid $7.92 for the 2.8km trip, which would have cost her at least $12 with a cab.

A security supervisor, who said he earns $2,400 a month, paid $8 for a 8km GrabCar ride from Golden Mile Tower to 112 Katong shopping centre. "It is affordable," he said.

A woman at IMM shopping mall going to Yew Tee, who booked me through GrabCar, asked whether I had any promotion code she could use. "You can try Googling," I replied, mildly amused.

A man in his 30s whom I picked up from a Havelock Road flat to his office at Marina Bay Financial Centre said: "I have stopped booking regular taxis."

BETTER EARNINGS THAN CABS?

The fares may be good for users, but not so much for me. On average, I collected $161 a day as an Uber driver - a quarter of which came from the financial incentives offered by the firm.

After deducting $50 for car rental and $25 for petrol, I earned $86 for about eight to nine hours of work. This works out to a monthly income of around $2,600.

Daily takings can be bumped up to $120 (which means a monthly income of $3,600), but that is only if I drive 10 to 12 hours. My daily earnings using GrabCar were similar.

A big reason for the lean fares was that demand for Uber and GrabCar dries up swiftly after the morning peak hours, before picking up again in the evening.

On one weekday morning after 10.30am, I drove 11km along Commonwealth Avenue passing through Queenstown, Holland Road, Ghim Moh and Clementi housing estates without a single booking on my GrabCar app.

The Uber surge during peak hours - when fares spike as demand does - also proved elusive.

On my first day, the app showed that there was a surge in demand in Buangkok which was five minutes away from my location, so I went for it. By the time I got there, the surge had ended.

Of my 44 Uber trips, 43 were in the morning and evening peak hours. And only two of them involved passengers paying additional surge fares. The extra I collected amounted to just $11.76.

Without incentives, the earnings from Uber and GrabCar fares were much less than from driving cabs.

And drivers who depend on incentives to boost their regular income put themselves at risk when the sweeteners change weekly, or even daily.

During my week's driving, Uber lowered its minimum hourly guaranteed peak hour fare from $18 to $17 an hour, while GrabCar bumped up drivers' fares during the peak hours by 25 per cent.

The incentives peaked on Christmas Eve, with GrabCar guaranteeing $25 for each trip and Uber promising $25 to $30 for each hour of driving that day. But this Uber bonus was unavailable on Christmas Day.

Uber's most appealing pitch to drivers is how they can drive a car that pays for itself. Its subsidiary Lion City Rentals rents out used cars at $58 to $62 each day for a minimum of five weeks and new cars at $71 to $82 each day for at least six months.

While these rental cars are cheaper than taxis, which cost $130 a day to rent, a driver still needs to put in at least four hours each day just to cover the cost of rental and petrol.

I also found several extra costs - a higher fuel bill, Uber and GrabCar's commission, the high insurance excess payment in the event of an accident, and waiting up to one week to be paid.

My daily petrol bill was about $25, roughly double that of diesel taxis since diesel costs about 40 per cent less a litre but gives about a third more mileage.

The 20 per cent commission to Uber and GrabCar was a bit of a downer. A hard-working driver who earns $200 in fares each day by driving more than 14 hours would lose $40 to Uber and GrabCar.

Work in the $80 rental for a new car and the higher fuel bill, the cost of running a new private-hire car works out to be the same as renting a new taxi.

There is also the worry about accidents. Car rental companies slap an excess of as high as $4,000, even if the driver is not at fault. A single accident could wipe out a month's earnings.

Demand for Uber and GrabCar rockets when it rains, but I stopped driving when the visibility was poor. The risk was just too high.

Uber fares are paid using credit cards and it calculates payment in weekly pay blocks from Monday to Sunday, paying out on Wednesday the following week.

And since some car rental companies deduct the weekly rent directly from Uber's payment and pay the driver the balance, it means another one or two days of waiting before one receives his earnings.

Several drivers I met said this was a reason why they preferred GrabCar - most of its passengers pay cash.

INCONSIDERATE PASSENGERS

While the peaks and troughs in daily demand were easy to get accustomed to, dealing with inconsiderate passengers was less so.

Most preferred to be left alone, with headphones glued to their ears and their eyes focused on their smartphones. Of the 88 passengers I ferried, only one addressed me by my name and asked whether I had my lunch.

My most pleasant encounter was with an American in his 40s, his pre-teenage son and their poodle called Hugo. They were chatty and said my car was very clean. Just before getting off at their swanky Nassim Hill condominium, the man bent down to straighten the car mat with his hands.

One GrabCar passenger in shorts and T-shirt - a man in his 20s who had a strong cigarette odour - took off his slippers as soon as he sat next to me. He tucked his left foot under his right knee, giving me a full view of the bare sole of his dirt-stained foot. It was not very nice.

Several passengers brought food into the car. One young couple heading to East Coast Park even started eating their McDonald's fries.

Several did not give exact details of their pick-up points. I had a GrabCar booking for a pick-up at simply "Lorong Telok", a 150m one-way street of shophouses. The passenger also had a Malaysian telephone number, which I could not get through to.

A handful disagreed with how I drove. One wanted me to drive against the flow of traffic at the basement carpark of her Jervois Road condominium, while another chided me when I drove against the flow of traffic by mistake at the basement carpark of her Holland Road condominium.

A woman that I picked up at a Cavenagh Road townhouse at 7.45pm on a Friday wanted to go to Duxton Hill "by the fastest way".

I told her that there was a massive jam in Orchard Road and Bras Basah Road, and I could avoid the jam by taking Bukit Timah Road and North Bridge Road. She agreed, but only to grumble later that I took a longer route.

Two passengers even directed me to break traffic rules - the one who wanted to be picked up along a red bus lane, and another who, after being picked up in Eu Tong Sen Street, insisted that I go straight on the left-turn-only lane.

The most annoying passengers were those who cancelled their bookings after I had accepted them.

The most unreasonable case was one in which I had already arrived at the Verge to pick a passenger up. She asked me on the phone to wait for her at a side road, which I did, only to cancel minutes later.

When I asked Uber about the cancellation, a helpdesk staff member pointed out its policy of allowing passengers to cancel bookings without penalties if they were made within five minutes. It did not matter that the driver had already arrived.

ALL A NUMBERS GAME

After a week on the road, I received a decent 4.76-star rating out of the maximum five for Uber. For GrabCar, it was 4.5 stars. I also accepted 85 per cent of the jobs assigned to me by Uber and 88 per cent of those by GrabCar. And I did not cancel a single job.

The numbers are vital because both Uber and GrabCar require a minimum four-star rating, and drivers accepting 85 and 70 per cent of jobs respectively, before they pay out weekly incentives.

Numbers apply to Uber passengers too. After each trip, drivers get to rate them. There is no real penalty for passengers, except that drivers may be less likely to accept bookings from those with poor ratings. GrabCar passengers do not get rated.

After I ended my driving stint, I found an online forum where Uber and GrabCar drivers hang out. It is awash with complaints about long hours spent on the road.

One forum member, who stopped driving with Uber after five weeks, wrote: "I drove for SMRT, TransCab and Premier. Taxiing (sic) full time can still send our kids to school. Ubering full-time you don't even have time for your kids."

Uber and GrabCar work for those who already have a car and are looking to earn some extra cash.

But for those who are drawn by the prospect of driving a personal car or to earn a living, it does mean long hours on the road.

In this sense, driving with Uber and GrabCar is not significantly different from driving cabs, even if the cars do not carry the taxi liveries.