lacking removal probably means punching harder... I subbed out the 3x harnessed lightnings to Fleetwheel Cruiser and a couple more dwarf pilots.
IMO shock and push aren't good in duels mardu vehicles. Duels don't have the good untapped lands to support the PT style vehicles aggro. It's not like vehicles consistently getting strong on curve plays and all you need T4-T5 is a shock or some finishing touch, or like you can play T2 push without screwing the mana base. When vehicles get slowed down by own tapped lands and opponent removals, not drawing gas becomes a painful issue for the archetype. When I play vehicles, I rarely felt "I need to clear up this blocker" but rather I usually die to not drawing enough vehicles or pilots. To me the only "must remove" target is Thalia. Otherwise I would prefer more pilots or vehicles to harnessed lightnings.
To improve threats density and push through damage, I went down the thopters and chief pump route. Right I play only 3 unconditional removals UD but good side for that - I could play 9 vehicles and 24 pilots. Within the 24 pilots, I have all thopter engineers and chiefs to make bigger and hasty flyers, making my vehicles and thopters attack easier so that I could care less about removing blockers. I don't think that automatically make my deck weak...
Joly goes even further by using those expensive midrange walkers, displacer and even the 2/1 angel. We had to lower the removal # in order to add these types of gas to vehicles deck to make it more powerful yet still explosive in Duels format, where without better lands, aggro can't really be that PT level consistent aggro.
Pretty much this. I went for a slower, more stable version of vehicles. You can't reproduce the explosiveness of the PT decks here consistently, so often the games slow down are just decided by dropping the bombs on curve (avacyn, invention, skyship, walkers, pia and kira). That also explains why I play so many lands, whenever I curve out I tend to win anyway.