At 3000 rpm in 5th you would actually be speeding

 

http://www.daciaforum.co.uk/forum/topic/2326-rpm-at-70/

You would be past 75 mph at 3000 rpm.

 

If you look in the Technical Specs section it gives you the mph / 1000rpm in each gear.

https://www.cdn.daciagroup.com/content/dam/Dacia/UK/Brochures/sandero-stepway-brochure.pdf

There is a small section on running in in the Drivers Handbook. Mine says for petrol engines for the first 600 miles do not exceed 78 mph in the highest gear or 3000 to 3500 rpm.

 

Thanks guys,will take another look at the handbook.????

 

Motorways aren't the best environments for running in an engine effectively, but sometimes needs must.
At 500 miles a modern engine is probably pretty much run in, so I wouldn't worry too much.
On a positive note, our 0.9 Stepway engine continued to smooth out and petrol consumption improved over the first 3K.

 

Thanks Pickaxe,that puts my mind at rest.
I have since worked out a route which will mean less motorway taking longer but kinder to the
young engine.