Hello Doni, and welcome to EcoModder
It looks like you are already on the right road to hypermiling. Have you tried pulse & glide? Try a lighter oil (for example 5W30) next time you change it.
The Volvo 244 is quite boxy, but a grille block and rear wheel skirts, plus a bellypan, should help. The grille block and underpan will also help the diesel engine get and stay warm.
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e·co·mod·ding: the art of turning vehicles into what they should be
What matters is
where you're going, not
how fast.
"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell
[Old] Piwoslaw's Peugeot 307sw modding thread