Forgot all about the road test, me and my dad had a good blast around outside his house and the cells seem pretty good! Definitely a lot faster than the tiring Alkaline AA’s my dad had in his car at first. Ran for quite a while (maybe 15 minutes or more?) with no sign of the batteries dumping.
The only thing I did notice was that the cells are a tight fit in the standard battery holder, I couldn’t get the holder lid on at all, but it didn’t matter as the cells were snug enough not to fall out.
All in all a decent cell for the car, good value too at approximately £5 for 4 from various eBay sellers.