Brazen scammers have been accused of pouring engine oil into a BMW's coolant system to make it billow with smoke on test drive before offering its owner a third of its price.
Bikramjit Kooner says two men who appeared keen to buy his car messed with it before attempting to land the 520D M Sport for less than half its value.
The pair turned up at home in Norwich, Norfolk, on Saturday before taking the vehicle for a spin.
But the dad-of-one says he soon became wary when one of the would-be buyers beckoned him round to the boot of the car, while the other stayed at the front.
Then, a few minutes into the test drive, the motor started to fill with thick smoke and the three men quickly drove back to Bikramjit's home.
They opened the bonnet where more smoke bloomed out, and the customers then allegedly offered to buy the car for £2,000 for "scrap" - nearly £4,000 less than what was advertised online.
Courier driver Bikramjit, 52, turned them down after checking the price with pals and, his suspicions still aroused, checked his CCTV - and was shocked with what he saw.
He claimed: "They put engine oil into the coolant system and poured used engine oil on the side of the engine.
"They pulled the air filter off so smoke could go straight inside the car before the test drive.
"I was thinking all night about when I left them alone to get the paperwork, but it was only 30 or 40 seconds. But luckily my camera was on record."
CCTV footage shows that, when one of the buyers had asked him to fetch some paperwork, they had popped open the bonnet and appeared to pour something in.
Bikramjit says they poured some oil into the BMW's coolant fluid.
And when Bikramjit returned with the paperwork he was distracted by one of the men around the back of the car, while the other splashed more liquid onto the engine and appeared to unclip the air filters, he alleges.
The seller contacted Norfolk Constabulary to report the crime, and enquiries are ongoing.
Luckily, Bikramjit did not go through with the sale, but he wants to share his story to protect others from falling for a similar alleged scam.
"I want to save other people, I know a little bit about cars but in 20 minutes I was almost brainwashed," he said.
"I was lucky I didn't sell it then. My friends said there's a lot of kind of people doing this stuff"I thought 'my God, how many people are doing this?'He put his 2012 car on Ebay on May 11 after two years of ownership, advertising it for £5,995.
On the morning of May 14, a man who claimed to be from London phoned him saying he was interested but wanted to negotiate the price, and the two agreed on £5,000, he says.
The buyer and a friend arrived at Bikramjit's garden at about 7pm that evening to inspect the silver vehicle and take it for a test drive.
Bikramjit says he found it strange that they said they had come from Cambridge, after earlier saying they were from London.
He said: "They looked normal.
"They said they had a similar car but had an accident and it was damaged in the front, and that's why they were buying a new car.
"They looked around the car, asked a few things and then for the papers.
"I had my car papers in my van parked on the driveway round the front, and in less than one minute they opened the bonnet.
"One man opened the coolant cap and the other man took something from his left side jacket pocket.
"He poured the oil into the coolant and, after, the other man put the cap back on the coolant.
"When I came back with the papers they quickly start talking about bumper and bonnet.
"One man stayed in front of the car and the other went behind it to open the boot and called me over.
"He started talking about the rear bumper and, in that time, the man in front tightened the coolant cap and poured more engine oil on side of the engine to make smoke.
"He also opened the top cover of the engine and lifted the air filter from the clips."
Unsuspecting Bikramjit then hopped into the car with one of the men for a test drive, but after a few minutes smoke started to fill the car.
He said: "I was scared because a few months ago we had to change the coolant seal and I thought it had failed.
"They wanted to stop and I said, 'no carry on, otherwise I have to tow it!'"
They quickly returned home and popped open the bonnet to be blasted with more smoke, before the two men told the shocked salesman that there was oil around the engine.
They apparently popped the cap off the coolant to reveal a layer of oil sitting on top of the fluid.
Bikramjit said: "They said, 'oh it's oil in water so your car engine is gone and the timing chain will break if you drive any more', and I thought same thing.
"He said 'your engine is f**cked!'"Then they tried to buy the car for as scrap for £2,000."
He refused to accept the offer, and they renegotiated to £3,500 before calling a couple of friends to check that this was still a worthwhile deal.
The pals told him that they could probably fix it for cheaper, and noted that something suspicious was likely going on.
"Everyone was asking me 'were you there all the time with the buyers?'" he said.
"So I didn't accept their offer for scrap but they did try their best. I noticed there was oil on the side, cover and the top of the engine.
"I told them at the time that I could see it on the bottom, but how is there oil on the top?"
With his friends' words echoing around his mind, Bikramjit decided to check the CCTV footage from the encounter the next day.
This is when he saw the two men allegedly tampering with the vehicle while he was retrieving paperwork, and when one of them distracted him by having a conversation in front of it.
He then tried to call them back but the phone was off, and so far has received no response from eBay after contacting customer services.
"I thought I was lucky I didn't take their offer," he said. "They tried hard, twenty minutes to half an hour, they wanted to take the car.
"If I didn't know I would have done the deal for £2,000."
Bikramjit has since taken the car to a mechanic who he said confirmed that the liquid was engine oil, but fortunately none of it had entered the car's mechanism so it was able to be flushed out.
Norfolk Constabulary have confirmed that their enquiries are ongoing.
