Newer 1.6 ones are rubbish. I've seen 3 year old ones scrapped, as the cost of anything major puts them over the typical 50% of value repair limit.There must be something up, given the number of dead vivaros there are for sale..
Costs over £5k to put a reconditioned engine in one, so any valued under £10k just get dragged to auction.
Commercially, repairing the engine isn't worth it.
17hr job to remove and refit a cylinder head, before you consider any other damage.
Leasing companies will take the view that if they have to pay 8hrs for a definitive diagnosis, and then still potentially pay another 11 to fit a new engine, they'll cut their losses (or bill the leaser for misuse if the data log shows it's been driven with various warning lights showing for several miles before melting).
Turbos regularly fail, and have been modified a few times.
Cooling system likes to spring leaks.
Hit anything with the front bumper, and it'll likely snap the radiator where the intercooler mounts, and push the intercooler pipe back so it rubs through on the alternator pulley.
I suspect Renault just took the engine from the car line where it was reasonably reliable, dumped it in a heavy van, and thought it would be just as reliable.
And I think Renault took the cheapest option they thought they could get away with on most components, given how many parts fail just outside warranty.
The older Trafic/Vivaro was pretty reliable, other than door handles, track rod ends, ball joints, and an occasional injector.