As said it can take anything from a few minutes to over 24 hours to transfer the money.

If the amount is large and the transfer is a new one from the sender then the senders bank may require verification, and or there will be a limit on the first transaction, so the actual transaction can take longer.

If he wants it, then it may be an idea for you to ask him to transfer a deposit over for the car, something small £100 say, this should then mean that the transfer of the rest of the cash should go through faster, as it will be a repeat transaction and you will get a steer as to how long the transfer should take.

when i sold my FF the guy gave me part cash and the rest was bank, it took until the next day for it to appear, but he was a person known to me and I know where he lives......so it wasn't a problem.

As stan said consult your bank on this, but once the money is in your account it can't be pulled back without you sending it back unless as has been said already fraud has taken place. There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

If you do a CHAPS payment it's instant and costs £25 - £30 depending on the bank.  2017 4.4 TDV8 Autobiography
2016 4.4 TDV8 Autobiography - GONE
2013 4.4 TDV8 Autobiography - GONE
2010 3.6 TDV8 - GONE
2008 3.6 TDV8 - GONE
2002 3.0 TD6 - GONE
2006 Discovery 3 TDV6 S - GONE
2006 Discovery 3 TDV6 - GONE
2003 Discovery 2 TD5 - GONE
1999 Discovery 300 TDI - GONE
1998 Range Rover DSE - GONE
1997 Discovery 300 TDI - GONE

Main dealers can't take cash! (Over a certain amount which I think is 8 grand) and some dealers (ford I think) won't take cash at all.

Think it was 6k when I bought mine..... There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

I did both the selling and buying of my recent Range Rovers with no problem there was a £20k limit with the recent purchase so I just did two with no problem (NatWest)

Unlike when I turned up at the dealer on a Saturday morning with a plastic bag full of cash to buy my wife a new fiesta.  Geoff

I once tried to pay by bank transfer, and my account limited me ( at the time ~2005 ) to £10k transaction per day.

Don't know if its changed since then, but it nearly caught me out. V8 or else ...

i've made and received lots of payments like this, only got stuck recently when i tried to pay for the new rr, transferred £1 just to check, then went for the balance and my bank referred to fraud dept and caused several hours delay / hassle. apparently fraudsters do this all the time and now banks software looking for this. would have been less hassle to transfer full amount in one go.