Printed voucher?

Is it necessary to have printed car rental voucher or will they accept phone screen?

If you are going direct to vehicle take a printed copy as they struggle to scan the barcode from my phone.

Although there is no requirement for printed voucher as long as you have the reference number, as Martin says it's sometimes easier to have it printed.

I collected a car from Dollar at West Palm Beach this evening and showed the email confirmation on my phone without any problem.